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

x^2 - 20 = x

a. 5, 4
b. -5, -4
c. -5, 4
d. 5, -4

Respuesta :

SaniShahbaz

Answer:

Option d is correct 5, -4

Step-by-step explanation:

Given equation x² - 20 = x

rewriting the above equation

x² - x - 20 = 0

[tex]x = \frac{-b +- \sqrt{b^{2}-4ac}}{2a}[/tex]

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

put values of a, b and c in the formula

[tex]x = \frac{-(-1) +- \sqrt{(-1)^{2}-4(1)(-20)}}{2(1)}[/tex]

[tex]x = \frac{1 +- \sqrt{1+80}}{2}[/tex]

[tex]x = \frac{1 +- \sqrt{81}}{2}[/tex]

[tex]x = \frac{1 +- 9}{2}[/tex]


[tex]x = \frac{1 + 9}{2}[/tex]

x = 5


[tex]x = \frac{1 - 9}{2}[/tex]

x = -4


alinakincsem

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:

[tex]x^2 - 20 = x[/tex]

Re-arranging this equation in order of decreasing power:

[tex]x^2-x-20=0[/tex]

Using the quadratic formula:

[tex] x = \frac {-b + - \sqrt{b^2 - 4ac} }{2a}[/tex]

Substituting the given values in the formula to get:

[tex]x=\frac{-(-1)+-\sqrt{(-1)^2-4(1)(-20)} }{2(1)}[/tex]

[tex]x=\frac{1+-\sqrt{81} }{2}[/tex]

[tex]x=\frac{1+\sqrt{81} }{2} , x= \frac{1-\sqrt{81}{2}[/tex]

[tex]x=5, x=-4[/tex]

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