Question

Complete the square to solve 2x2 + 20x = 10.

O A. x = 51,30
O B. x= -530
O C. *= -21VTO
O D. X = 2 + 15

Answer 1

x = -5 +
`√(30)` or x = -5 -
`√(30)`

x is about 0.4772 or x = - 10.4772

Explanation:

Start with the equation: 2 * x^2 + 20x = 10

We can divide both sides by 2.

We get: x^2 + 10x = 5

Let us find the number to complete the square on the left side

(10/2)^2 = 5^2 = 25

Add 25 to both sides

x^2 + 10x + 25 = 5 + 25

(x + 5)^2 = 30 , now I can replace the trinomial x^2 + 10x + 25 with the binomail squared (x + 5)^2

Now we solve for x

Take square root of both sides.

x + 5 =
`√(30)` or x + 5 = -
`√(30)`

We get two equations because taking the square root of a number yields a plus and negative number.

x = -5 +
`√(30)` or x = -5 -
`√(30)`

x is about 0.4772 or x = - 10.4772