Question

Solve the inequality and express in interval notation x^2 + 8x + 5 < 0

Answer 1

Hello from MrBillDoesMath!

Answer:

x > -4 - sqrt(11) and x < -4 + sqrt(11)

Discussion:

Let's complete the square by adding and subtracting the value 16 from both sides

x^2 + 8x + 5 < 0 =>

(x^2 + 8x + 16) + 5 < 0 + 16 => complete the square

(x + 4) ^2 + 5 < 16 => subtract 5 from both sides

(x+4)^2 < 16 - 5 = 11 => take square root of both sides

(x+4) > -sqrt(11) and ( x+4 ) < sqrt(11) =>

x > -4 - sqrt(11) and x < -4 + sqrt(11)

Thank you,

MrB