Question

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

Answer 1

Answer:

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

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

$(x+2)=\pm\sqrt{\frac{27}{5}}$

Step-by-step 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

$(x+2)^2=\frac{27}{5}$

$(x+2)=\pm\sqrt{\frac{27}{5}}$

$(x+2)=\pm\frac{3\sqrt{15}}{5}$

step 6

$x=-2\pm\frac{3\sqrt{15}}{5}$

Answer 2

Answer:

b, c, and d

Step-by-step explanation:

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