If 𝑓 of 𝑥 equals five plus three
𝑥, which of the following is equivalent to 𝑓 of negative three 𝑥?
We’re starting out with 𝑓 of 𝑥
equals five plus three 𝑥. And we need to plug in negative
three 𝑥 for the 𝑥-value. This means that anywhere in our
function where 𝑥 shows up we need to replace it with negative three 𝑥. After we do that, we can simplify
the second function, bring down the five. We can multiply three by negative
three, which gives negative nine and that’s been multiplied by 𝑥.
We could also think of it another
way. We could think of it as multiplying
the 𝑥 that’s there by negative three. And in that case, every place we
see 𝑥, we would need to multiply that 𝑥 by negative three. The expression would then be three
times negative three times 𝑥. And that simplifies to negative
The only answer choice that
reflects this expression is c five minus nine 𝑥.