SOLUTION: Solve the inequality and express the solution set in interval notation. x^2 + 6x -16 is less than 0 Please help! Thanks, Alicia

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Question 881962: Solve the inequality and express the solution set in interval notation.
x^2 + 6x -16 is less than 0
Please help!
Thanks,
Alicia
Answer by josgarithmetic(39615) About Me  (Show Source):
You can put this solution on YOUR website!
x%5E2+%2B+6x+-16+%3C+0

Find the roots or zeros for the quadratic expression. The two roots are the critical values for the three intervals of x. Test each interval (pick any value in each interval and test the value and find if the chosen critical value makes the inequality true or makes the inequality false).

THAT quadratic expression is factorable:
x%5E2%2B6x-16=%28x-2%29%28x%2B8%29%3C0; the critical values for x are -8 and 2. The vertex is a minimum, and must be both between the two critical values AND below the x-axis, meaning ,less than zero for y. This means that the solution for x will be the strict inequality, highlight%28-8%3Cx%3C2%29.