Step by Step Solution
Step by step solution :
Step 1 :
Equation at the end of step 1 :
1 (((—•(x3))-2x2)+3x)+1 = 0 3Step 2 :
1 Simplify — 3
Equation at the end of step 2 :
1
(((— • x3) - 2x2) + 3x) + 1 = 0
3
Step 3 :
Equation at the end of step 3 :
x3
((—— - 2x2) + 3x) + 1 = 0
3
Step 4 :
Rewriting the whole as an Equivalent Fraction :
4.1 Subtracting a whole from a fraction
Rewrite the whole as a fraction using 3 as the denominator :
2x2 2x2 • 3
2x2 = ——— = ———————
1 3
Equivalent fraction : The fraction thus generated looks different but has the same value as the whole
Common denominator : The equivalent fraction and the other fraction involved in the calculation share the same denominator
Adding fractions that have a common denominator :
4.2 Adding up the two equivalent fractions
Add the two equivalent fractions which now have a common denominator
Combine the numerators together, put the sum or difference over the common denominator then reduce to lowest terms if possible:
x3 - (2x2 • 3) x3 - 6x2
—————————————— = ————————
3 3
Equation at the end of step 4 :
(x3 - 6x2)
(—————————— + 3x) + 1 = 0
3
Step 5 :
Rewriting the whole as an Equivalent Fraction :
5.1 Adding a whole to a fraction
Rewrite the whole as a fraction using 3 as the denominator :
3x 3x • 3
3x = —— = ——————
1 3
Step 6 :
Pulling out like terms :
6.1 Pull out like factors :
x3 - 6x2 = x2 • (x - 6)
Adding fractions that have a common denominator :
6.2 Adding up the two equivalent fractions
x2 • (x-6) + 3x • 3 x3 - 6x2 + 9x
——————————————————— = —————————————
3 3
Equation at the end of step 6 :
(x3 - 6x2 + 9x)
——————————————— + 1 = 0
3
Step 7 :
Rewriting the whole as an Equivalent Fraction :
7.1 Adding a whole to a fraction
Rewrite the whole as a fraction using 3 as the denominator :
1 1 • 3
1 = — = —————
1 3
Step 8 :
Pulling out like terms :
8.1 Pull out like factors :
x3 - 6x2 + 9x = x • (x2 - 6x + 9)
Trying to factor by splitting the middle term
8.2 Factoring x2 - 6x + 9
The first term is, x2 its coefficient is 1 .
The middle term is, -6x its coefficient is -6 .
The last term, "the constant", is +9
Step-1 : Multiply the coefficient of the first term by the constant 1 • 9 = 9
Step-2 : Find two factors of 9 whose sum equals the coefficient of the middle term, which is -6 .
| -9 | + | -1 | = | -10 | ||
| -3 | + | -3 | = | -6 | That's it |
Step-3 : Rewrite the polynomial splitting the middle term using the two factors found in step 2 above, -3 and -3
x2 - 3x - 3x - 9
Step-4 : Add up the first 2 terms, pulling out like factors :
x • (x-3)
Add up the last 2 terms, pulling out common factors :
3 • (x-3)
Step-5 : Add up the four terms of step 4 :
(x-3) • (x-3)
Which is the desired factorization
Multiplying Exponential Expressions :
8.3 Multiply (x-3) by (x-3)
The rule says : To multiply exponential expressions which have the same base, add up their exponents.
In our case, the common base is (x-3) and the exponents are :
1 , as (x-3) is the same number as (x-3)1
and 1 , as (x-3) is the same number as (x-3)1
The product is therefore, (x-3)(1+1) = (x-3)2
Adding fractions that have a common denominator :
8.4 Adding up the two equivalent fractions
x • (x-3)2 + 3 x3 - 6x2 + 9x + 3
—————————————— = —————————————————
3 3
Checking for a perfect cube :
8.5 x3 - 6x2 + 9x + 3 is not a perfect cube
Trying to factor by pulling out :
8.6 Factoring: x3 - 6x2 + 9x + 3
Thoughtfully split the expression at hand into groups, each group having two terms :
Group 1: 9x + 3
Group 2: -6x2 + x3
Pull out from each group separately :
Group 1: (3x + 1) • (3)
Group 2: (x - 6) • (x2)
Bad news !! Factoring by pulling out fails :
The groups have no common factor and can not be added up to form a multiplication.
Polynomial Roots Calculator :
8.7 Find roots (zeroes) of : F(x) = x3 - 6x2 + 9x + 3
Polynomial Roots Calculator is a set of methods aimed at finding values of x for which F(x)=0
Rational Roots Test is one of the above mentioned tools. It would only find Rational Roots that is numbers x which can be expressed as the quotient of two integers
The Rational Root Theorem states that if a polynomial zeroes for a rational number P/Q then P is a factor of the Trailing Constant and Q is a factor of the Leading Coefficient
In this case, the Leading Coefficient is 1 and the Trailing Constant is 3.
The factor(s) are:
of the Leading Coefficient : 1
of the Trailing Constant : 1 ,3
Let us test ....
| P | Q | P/Q | F(P/Q) | Divisor | |||||
|---|---|---|---|---|---|---|---|---|---|
| -1 | 1 | -1.00 | -13.00 | ||||||
| -3 | 1 | -3.00 | -105.00 | ||||||
| 1 | 1 | 1.00 | 7.00 | ||||||
| 3 | 1 | 3.00 | 3.00 |
Polynomial Roots Calculator found no rational roots
Equation at the end of step 8 :
x3 - 6x2 + 9x + 3
————————————————— = 0
3
Step 9 :
When a fraction equals zero :
9.1 When a fraction equals zero ...Where a fraction equals zero, its numerator, the part which is above the fraction line, must equal zero.
Now,to get rid of the denominator, Tiger multiplys both sides of the equation by the denominator.
Here's how:
x3-6x2+9x+3
——————————— • 3 = 0 • 3
3
Now, on the left hand side, the 3 cancels out the denominator, while, on the right hand side, zero times anything is still zero.
The equation now takes the shape :
x3-6x2+9x+3 = 0
Cubic Equations :
9.2 Solve x3-6x2+9x+3 = 0
Future releases of Tiger-Algebra will solve equations of the third degree directly.
Meanwhile we will use the Bisection method to approximate one real solution.
Approximating a root using the Bisection Method :
We now use the Bisection Method to approximate one of the solutions. The Bisection Method is an iterative procedure to approximate a root (Root is another name for a solution of an equation).
The function is F(x) = x3 - 6x2 + 9x + 3
At x= -1.00 F(x) is equal to -13.00
At x= 0.00 F(x) is equal to 3.00
Intuitively we feel, and justly so, that since F(x) is negative on one side of the interval, and positive on the other side then, somewhere inside this interval, F(x) is zero
Procedure :
(1) Find a point "Left" where F(Left) < 0
(2) Find a point 'Right' where F(Right) > 0
(3) Compute 'Middle' the middle point of the interval [Left,Right]
(4) Calculate Value = F(Middle)
(5) If Value is close enough to zero goto Step (7)
Else :
If Value < 0 then : Left <- Middle
If Value > 0 then : Right <- Middle
(6) Loop back to Step (3)
(7) Done!! The approximation found is Middle
Follow Middle movements to understand how it works :
Left Value(Left) Right Value(Right) -1.000000000 -13.000000000 0.000000000 3.000000000 -1.000000000 -13.000000000 0.000000000 3.000000000 -0.500000000 -3.125000000 0.000000000 3.000000000 -0.500000000 -3.125000000 -0.250000000 0.359375000 -0.375000000 -1.271484375 -0.250000000 0.359375000 -0.312500000 -0.428955078 -0.250000000 0.359375000 -0.281250000 -0.028106689 -0.250000000 0.359375000 -0.281250000 -0.028106689 -0.265625000 0.167293549 -0.281250000 -0.028106689 -0.273437500 0.070009708 -0.281250000 -0.028106689 -0.277343750 0.021055758 -0.279296875 -0.003499381 -0.277343750 0.021055758 -0.279296875 -0.003499381 -0.278320312 0.008784707 -0.279296875 -0.003499381 -0.278808594 0.002644293 -0.279052734 -0.000427137 -0.278808594 0.002644293 -0.279052734 -0.000427137 -0.278930664 0.001108680 -0.279052734 -0.000427137 -0.278991699 0.000340797 -0.279022217 -0.000043164 -0.278991699 0.000340797 -0.279022217 -0.000043164 -0.279006958 0.000148818 -0.279022217 -0.000043164 -0.279014587 0.000052828 -0.279022217 -0.000043164 -0.279018402 0.000004832 -0.279020309 -0.000019166 -0.279018402 0.000004832 -0.279019356 -0.000007167 -0.279018402 0.000004832 -0.279018879 -0.000001167 -0.279018402 0.000004832
Next Middle will get us close enough to zero:
F( -0.279018760 ) is 0.000000333
The desired approximation of the solution is:
x ≓ -0.279018760
Note, ≓ is the approximation symbol
Supplement : Solving Quadratic Equation Directly
Solving x2 - 6x + 9 = 0 directly Earlier we factored this polynomial by splitting the middle term. let us now solve the equation by Completing The Square and by using the Quadratic Formula
Parabola, Finding the Vertex :
10.1 Find the Vertex of y = x2-6x+9
Parabolas have a highest or a lowest point called the Vertex . Our parabola opens up and accordingly has a lowest point (AKA absolute minimum) . We know this even before plotting "y" because the coefficient of the first term, 1 , is positive (greater than zero).
Each parabola has a vertical line of symmetry that passes through its vertex. Because of this symmetry, the line of symmetry would, for example, pass through the midpoint of the two x -intercepts (roots or solutions) of the parabola. That is, if the parabola has indeed two real solutions.
Parabolas can model many real life situations, such as the height above ground, of an object thrown upward, after some period of time. The vertex of the parabola can provide us with information, such as the maximum height that object, thrown upwards, can reach. For this reason we want to be able to find the coordinates of the vertex.
For any parabola,Ax2+Bx+C,the x -coordinate of the vertex is given by -B/(2A) . In our case the x coordinate is 3.0000
Plugging into the parabola formula 3.0000 for x we can calculate the y -coordinate :
y = 1.0 * 3.00 * 3.00 - 6.0 * 3.00 + 9.0
or y = 0.000
Parabola, Graphing Vertex and X-Intercepts :
Root plot for : y = x2-6x+9
Vertex at {x,y} = { 3.00, 0.00}
x-Intercept (Root) :
One Root at {x,y}={ 3.00, 0.00}
Note that the root coincides with
the Vertex and the Axis of Symmetry
coinsides with the line x = 0
Solve Quadratic Equation by Completing The Square
10.2 Solving x2-6x+9 = 0 by Completing The Square .
Subtract 9 from both side of the equation :
x2-6x = -9
Now the clever bit: Take the coefficient of x , which is 6 , divide by two, giving 3 , and finally square it giving 9
Add 9 to both sides of the equation :
On the right hand side we have :
-9 + 9 or, (-9/1)+(9/1)
The common denominator of the two fractions is 1 Adding (-9/1)+(9/1) gives 0/1
So adding to both sides we finally get :
x2-6x+9 = 0
Adding 9 has completed the left hand side into a perfect square :
x2-6x+9 =
(x-3) • (x-3) =
(x-3)2
Things which are equal to the same thing are also equal to one another. Since
x2-6x+9 = 0 and
x2-6x+9 = (x-3)2
then, according to the law of transitivity,
(x-3)2 = 0
We'll refer to this Equation as Eq. #10.2.1
The Square Root Principle says that When two things are equal, their square roots are equal.
Note that the square root of
(x-3)2 is
(x-3)2/2 =
(x-3)1 =
x-3
Now, applying the Square Root Principle to Eq. #10.2.1 we get:
x-3 = √ 0
Add 3 to both sides to obtain:
x = 3 + √ 0
The square root of zero is zero
This quadratic equation has one solution only. That's because adding zero is the same as subtracting zero.
The solution is:
x = 3
Solve Quadratic Equation using the Quadratic Formula
10.3 Solving x2-6x+9 = 0 by the Quadratic Formula .
According to the Quadratic Formula, x , the solution for Ax2+Bx+C = 0 , where A, B and C are numbers, often called coefficients, is given by :
- B ± √ B2-4AC
x = ————————
2A
In our case, A = 1
B = -6
C = 9
Accordingly, B2 - 4AC =
36 - 36 =
0
Applying the quadratic formula :
6 ± √ 0
x = ————
2
The square root of zero is zero
This quadratic equation has one solution only. That's because adding zero is the same as subtracting zero.
The solution is:
x = 6 / 2 = 3
One solution was found :
x ≓ +0.279018760How did we do?
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