Question

Determine f(5)
f(x)=2x'2-1 if x < or equal to -1
3x+2 if x > -1

Answer 1

To make it clearer, I just put every thing under the formal form

f(x) =
`\left \{ {{2x^2-1~~~~if~~~~ x\leq -1} \atop {3x+2~~~~~if~~~~~x>-1}} \right.`

Explanation:

Now, you have 2 equations with 2 conditions. One is > -1, and one is < -1.

The question is about f (5). So, which equation you use to replace x = 5? The first one or the second one? and why?

Answering those questions help you understand how it works.