Question

What is f(–3) if f(x) = |2x + 1| + 5? can someone help with this .i'll give medal :)

Answer 1

you just need to plug in -3 instead of x into the function.

Answer 2

\(\large\color{black}{ f(x) = \left| 2x + 1 \right| + 5 }\)
For example, if I wanted to find, \(\large\color{black}{ f(-5) }\), this is what I do:

\(\large\color{black}{ f(\color{red}{-5}) = \left| 2(\color{red}{-5}) + 1 \right| + 5 }\)
\(\large\color{black}{ f(\color{red}{-5}) = \left| -10+ 1 \right| + 5 }\)
\(\large\color{black}{ f(\color{red}{-5}) = \left| -9 \right| + 5 }\)

then you know that for any positive number \(\large\color{black}{ a }\),
\(\large\color{black}{ \left| -a \right| =a }\)

So, you get,
\(\large\color{black}{ f(\color{red}{-5}) = 9 + 5 }\)
\(\large\color{blue}{ f(\color{red}{-5}) = 14 }\)

Answer 3

oh ok thank you

Answer 4

Anytime!