Question

The square of a number added to 2 times a number is 8. Find the number.

Answer 1

x = -4 or 2

Explanation:

Let the number be x.

Given condition:

x² + 2x = 8

Subtract 8 to both sides

x² + 2x - 8 = 0

Using mid-term break method

=> 4 × -2 = 8 (side-term), 4 - 2 = 2 (mid-term)

So, we can break the mid-term into 4 and -2.

x² + 4x - 2x - 8 = 0

Take common

x(x + 4) - 2(x + 4) = 0

Take (x+4) common

(x+4)(x-2) = 0

Either

x + 4 = 0 OR x - 2 = 0 (Zero's method)

x = -4 OR x = 2

`\rule[225]{225}{2}`