Question

Completing the Square

2. Solve the equation by completing the square. Show your work.
x2 – 30x = –125
Step 1: Add (b/2)^2 to both sides of the equation. (2 points)


Step 2: Factor the left side of the equation. Show your work. (2 points)
Hint: It is a perfect square trinomial.



Step 3: Take the square root of both sides of the equation from Step 2. (1 point)


Step 4: Simplify the radical and solve for x. Show your work. (1 point)

Answer 1

See below

Explanation:

Step 1

x^2 – 30x = –125

-30/2 = -15

(-15)^2 = 225

Step 2

x^2 -30x+225 = -125+225

(x-15)^2 = 100

Step 3

Take the square root of each side

sqrt((x-15)^2) = sqrt(100)

Step 4

x-15 = ±10

x-15 =10 x-15 = -10

x= 10+15 x = -10 +15

x = 25 x = 5