Question

Sergey is solving 5x2 + 20% – 7 = 0. Which steps could he use to solve the quadratic equation by completing the

square? Select three options.
5(x2 + 4x + 4) = -7 + 20
X+2 = + 27
5(x2 + 4x) = 7
5(x2 + 4x + 4) = 7 + 20
5(x2 + 4x) = -7

Answer 1

b, c, and d

Explanation:

I took the test

Answer 2

`5(x^2+4x)=7`

`5(x^2+4x+4)=7+20`

`(x+2)=\pm\sqrt{(27)/(5)}`

Explanation:

we have

`5x^2+20x-7=0`

step 1

Group terms that contain the same variable, and move the constant to the opposite side of the equation

`5x^2+20x=7`

step 2

Factor 5 left side

`5(x^2+4x)=7`

step 3

Complete the square

`5(x^2+4x+2^2)=7+2^2(5)`

`5(x^2+4x+4)=7+20`

`5(x^2+4x+4)=27`

step 4

Rewrite as perfect squares

`5(x+2)^2=27`

step 5

`(x+2)^2=(27)/(5)`

`(x+2)=\pm\sqrt{(27)/(5)}`

`(x+2)=\pm(3√(15))/(5)`

step 6

`x=-2\pm(3√(15))/(5)`