Solve Quadratic Equations by Taking the Square Root

When solving a quadratic equation, when do you use the plus or minus (±) symbol?

• After taking the square root of both sides

• After adding the square to both sides

• After taking half of b

• After setting the equation equal to zero

2x²=100

• x = √25

• x = ±5√2

• x = √100

• x = ±√5

Solve

x² + 2x - 20 = 4

• x = -6, x = 4

• x = 6, x = -4

• x = 12, x = -2

• x = 8, x = -3

(2x - 4)² = 16

• x = 4

• x = 10

• x = -2

• x = 0, 4

Solve using square roots.

• ±81

• ±9

• ±3

• No real solution

Find the zero(s) by taking square roots.