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Solution - Solving quadratic inequalities using the quadratic formula

Interval notation - No Real Roots: x(,)
x∈(-∞,∞)
Solution: x1=i·322,x2=-i·322
x_{1}=i\cdot\sqrt{322} , x_{2}=-i\cdot\sqrt{322}

Step-by-step explanation

1. Simplify the quadratic inequality into its standard form

ax2+bx+c0

Subtract 180 from both sides of the inequality:

x2+502180

Subtract 180 from both sides:

x2+502180180180

Simplify the expression

x2+3220

2. Determine the quadratic inequality's coefficients a, b and c

The coefficients of our inequality, x2+0x+3220, are:

a = 1

b = 0

c = 322

3. Plug these coefficients into the quadratic formula

To find the roots of a quadratic equation, plug its coefficients (a, b and c ) into the quadratic formula:

x=(-b±sqrt(b2-4ac))/(2a)

a=1
b=0
c=322

x=(-0±sqrt(02-4*1*322))/(2*1)

Simplify the exponents and square roots

x=(-0±sqrt(0-4*1*322))/(2*1)

Perform any multiplication or division, from left to right:

x=(-0±sqrt(0-4*322))/(2*1)

x=(-0±sqrt(0-1288))/(2*1)

Calculate any addition or subtraction, from left to right.

x=(-0±sqrt(-1288))/(2*1)

Perform any multiplication or division, from left to right:

x=(-0±sqrt(-1288))/(2)

to get the result:

x=(-0±sqrt(-1288))/2

4. Simplify square root (1288)

Simplify 1288 by finding its prime factors:

The prime factorization of -1288 is 2i·322

The square root of a negative number does not exist among the set of Real Numbers. We introduce The imaginary number "i", which is the square root of negative one. (1)=i

-1288=(-1)·1288

(-1)·1288=i1288

Write the prime factors:

i1288=i2·2·2·7·23

Group the prime factors into pairs and rewrite them in exponent form:

i2·2·2·7·23=i22·2·7·23

Use the rule (x2)=x to simplify further:

i22·2·7·23=2i·2·7·23

Perform any multiplication or division, from left to right:

2i·2·7·23=2i·14·23

2i·14·23=2i·322

5. Solve the equation for x

x=(-0±2i*sqrt(322))/2

The ± means two roots are possible.

Separate the equations:
x1=(-0+2i*sqrt(322))/2 and x2=(-0-2i*sqrt(322))/2

x1=(0+2i·322)2

Simplify the arithmetic:

x1=2i·3222

Simplify the fraction:

x1=i·322

x2=(0-2i·322)2

Simplify the arithmetic:

x2=-2i·3222

Simplify the fraction:

x2=-i·322

6. Find the intervals

Discriminant part of the quadratic formula:

b24ac<0 There are no real roots.
b24ac=0 There is one real root.
b24ac>0 There are two real roots.

Inequality function has no real roots, the parabola does not intersect with the x-axis. The quadratic formula requires taking the square root, and square root of negative number is not defined over the real line.

Interval is (,)

Why learn this

Whereas quadratic equations express the paths of arcs and the points along them, quadratic inequalities express the areas within and outside of these arcs and the ranges they cover. In other words, if quadratic equations tell us where the boundary is, then quadratic inequalities help us understand what we should focus on relative to that boundary. More practically, quadratic inequalities are used to create complex algorithms that fuel powerful software and to track how changes, such as prices at the grocery store, happen over time.

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