Evaluating functions, step by step
f(4) is a name for a value, not f times 4.
The question
Find f(−6).
f(x) = −3x + 10; f(−6)
f(x) = −3x + 10atx = −6
−3 × (−6)=18
18+10=28
f(−6)=28
- f(−6) is a name for the value of the rule when x = −6. Put −6 where the x is — it is not f times −6.
- Multiply first, sign and all: −3 × (−6) = 18.
- Then add 10: 18 + 10 = 28.
- So f(−6) = 28.
How it works.
- 01
f(−6) is a name for the value of the rule when x = −6. Put −6 where the x is — it is not f times −6.
- 02
Multiply first, sign and all: −3 × (−6) = 18.
- 03
Then add 10: 18 + 10 = 28.
- 04
So f(−6) = 28.