Question

Solve this equation by completing the square: x2 + 4x – 13 = –8

Answer 1

Answer:

x = 1 or x = -5

Step-by-step explanation:

We are given;

• The quadratic equation, x² + 4x - 13 = -8

We are required to solve the equation using the completing square method.

To do this, we use the following steps;

Step 1: We make sure the coefficient of x² is one

x² + 4x - 13 = -8

Step 2: Combine the like terms (take the constant term to the other side)

x² + 4x - 13 = -8

x² + 4x = -8 + 13

we get

x² + 4x  = 5

Step 3: We add the square of half the coefficient of x on both sides of the equation

Coefficient of x = 4

Half of coefficient of x = 2

Square of half the coefficient of x = 2² (4)

We get;

x² + 4x + (2²)  = 5 + (2²)

Step 4: Put x and 2 under one square and the solve the other side of the equation.

We get

(x + 2)² = 5 + 4

(x + 2)² = 9

Step 5: Get the square root on both sides of the equation;

(x + 2)² = 9

√(x + 2)² = ±√9

(x + 2)= ±3

Therefore;

x+2 = + 3 or x + 2 = -3

Thus, x = 1 or -5

The solution of the equation is x = 1 or x = -5