Question

Which are the solutions of x^2 =-7x-8

Answer 1

x 2 + 7 x − 8 = ( x − 1 ) ( x + 8 )

Explanation:

Given

x 2 + 7 x − 8

Note that the sum of the coefficients is 0

That is 1 + 7 − 8 = 0

So x = 1 is a zero and ( x − 1 )

a factor: x 2 + 7 x − 8 = ( x − 1 ) ( x + 8 )

The linear factor ( x + 8 ) can be constructed by looking at the coefficients of

x 2 and the constant term − 8

that we want in the product:

Since the coefficient of x 2 is 1 in the product, we require a coefficient

1 for x

Since the constant term is − 8 in the product, we require a constant + 8

in the factor which will become − 8 when multiplied by − 1