If f(x) = -6x - 3f(x)=−6x−3, then how do you find f(2)?

2 Answers
Gió
Jul 2, 2015

f(2)=-15f(2)=−15

Explanation:

Substitute 22 instead of xx into your function so you get:
f(2)=(-6*2)-3=-12- 3=-15f(2)=(−6⋅2)−3=−12−3=−15

Jim H
Jul 2, 2015

Replace every xx with 22 and do the arithemetic.

Explanation:

In the definition of this function the variable xx is a name for the blank space. (Definition for the rest of this one problem, not for other problems too.)

fcolor(red)((x)) = -6 color(red)((x)) -3f(x)=−6(x)−3

To find f(2)f(2), replace all of the xx'swith 22 and do the arithmetic.

fcolor(red)((2)) = -6 color(red)((2)) -3f(2)=−6(2)−3

Now we do the arithmetic:

f(2) = -6(2) -3 = -12 - 3 = -15f(2)=−6(2)−3=−12−3=−15

Here's another example: for the same ff, find f(-5)f(−5)

Solution:
fcolor(red)((-5)) = -6 color(red)((-5)) -3f(−5)=−6(−5)−3

= 30-3=30−3
= 27=27

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