Question

Use the quadratic formula to solve the equation. If necessary, round to the nearest hundredth.

Answer 1

Answer:

The correct answer option is d. 5, -4.

Step-by-step explanation:

We are given the following equation and we are to solve it using the quadratic formula:

$x^2 - 20 = x$

Re-arranging this equation in order of decreasing power:

$x^2-x-20=0$

Using the quadratic formula:

$x = \frac {-b + - \sqrt{b^2 - 4ac} }{2a}$

Substituting the given values in the formula to get:

$x=\frac{-(-1)+-\sqrt{(-1)^2-4(1)(-20)} }{2(1)}$

$x=\frac{1+-\sqrt{81} }{2}$

$x=\frac{1+\sqrt{81} }{2} , x= \frac{1-\sqrt{81}{2}$

$x=5, x=-4$

Answer 2

Answer:

Option d is correct 5, -4

Step-by-step explanation:

Given equation x² - 20 = x

rewriting the above equation

x² - x - 20 = 0

$x = \frac{-b +- \sqrt{b^{2}-4ac}}{2a}$

where a = 1; b = -1; c = -20

put values of a, b and c in the formula

$x = \frac{-(-1) +- \sqrt{(-1)^{2}-4(1)(-20)}}{2(1)}$

$x = \frac{1 +- \sqrt{1+80}}{2}$

$x = \frac{1 +- \sqrt{81}}{2}$

$x = \frac{1 +- 9}{2}$

$x = \frac{1 + 9}{2}$

x = 5

$x = \frac{1 - 9}{2}$

x = -4