For what values of x is x2-36=5x true? -9 and -4 -4 and 9 4 and -9 9 and 4

Question

asked Oct 20, 2020 138k views

2 Answers

Shervin Asgari · Answer 1 · 2020-10-25T05:54:06+0000

Answer: SECOND OPTION

Explanation:

Given the following equation:

x^2-36=5x

You can follow these steps in order to find the values of "x" that makes the equation true:

1. Subtract
from both sides of the equation:

$x^2-36-5x=5x-5x\\\\x^2-5x-36=0$

2. Factor the equation. Find two numbers whose sum be -5 and whose product be -36. These are 4 and -9:

(x+4)(x-9)=0

Then you get:

$x_1=-4\\\\x_2=9$

Checking:

$(-4)^2-36=5(-4)\\\\-20=-20$

TRUE

$(9)^2-36=5(9)\\\\45=45$

TRUE