Heather A. answered • 10/10/17
Tutor
New to Wyzant
Math and Physics, Middle School to College
The notation f(x-1) does not get evaluated. If x=-3, just substitute and do the arithmetic. So,
f(x-1)=2x-3 and x=-3
f(-3-1)=2(-3)+3
f(-4)=-6+3
f(-4) = -3
Therefore the answer is -3, not -1. And f(-4) remains as is.
Ali H.
f(−3) = f(−2 – 1) = 2(−2) + 3, and so the value of f(−3) is −1.
Alternatively: 2x + 3 can be rewritten as 2(x – 1) + 5, and since f(x – 1) = 2(x – 1) + 5
for all values of x, it follows that f(x) = 2x + 5 for all values of x. Substituting −3 for x
in this equation gives f(−3) = 2(−3) + 5 = –1.
Choices A, B, and C are incorrect because f is a function, and there is one and only
one value for f(−3), which as shown above is −1. Therefore, neither of the choices,
−7, −5, or −3 can be the value of f(−3).
10/10/17