Question

Let f(x)=7x+2 and g(x)=2x^2-x-1.
Compute: 5f(-1)-3g(-2)
Would the f(x) and g(x) formula fit in between the letter and number? How would I be able to do this step by step?

Answer 1

f(-1) just means you plug in -1 wherever there is an x in your function, so f(-1) = 7(-1)+2

Answer 2

So do it just like how you did the other problem, except we will multiply f(-1) by 5, and g(-2) by -3 .

Answer 3

and yes you're multiplying them by the function

Answer 4

So the 5f and 3g are the final steps?

Answer 5

Yes . Just remember it's -3 .

Answer 6

\[\color{red}{f(-1)=7(-1)+2} ~,~~ \color{blue}{g(-2)=2(-2)^2-(-2)-1}\]\[5(\color{red}{f(-1)})-3(\color{blue}{g(-2)})\]

Answer 7

I had -4 as my answer?

Answer 8

That is not what I am getting.

Answer 9

I don't get that

Answer 10

hmm.. I am truly am bad at math. I guess I'll try to recalculate all that ><

Answer 11

First solve for f(-1), highlighted in red. Then do the same for g(-2) highlighted in blue

Answer 12

Oh wait multiply 9 by 3

Answer 13

Take your highlighted answers and just plug them into 5( ) - 3( )

Answer 14

Yes that should be -5 :P

Answer 15

@Astrophysics 7(-1) + 2 = -5 not 5

Answer 16

-2 ><

Answer 17

You can check the arithmetic

Answer 18

@shawmoes not -9 should be 9

Answer 19

Yeah, -2 sounds good :)

Answer 20

@triciaal Ahh yes, slip of the keyboard.

Answer 21

Uhggg

Answer 22

No not -2

Answer 23

f(-1) = 7(-1)+2 = -5
5*-5 = -25
g(-2) = 2(-2)^2 -(-2)-1 = 9
3(9) = 27

-25-27 =...

Answer 24

Damn signs haha!

Answer 25

oh damn. Wait -52 0-0

Answer 26

@reinatrumpet26 the process is correct.

Answer 27

The problem of doing problems without latex, screws everything up :P

Answer 28

The problem is too many answerers , and then looking at their work and making a mistake because of their mistake ahaha.

Answer 29

Ok.

-25-27 = - (25 + 27) = ?

This is seriously not another 9 + 10 = 21 thing.

Come on people

Answer 30

Yeah, I kept scrolling up and realizing there were arithmetic mistakes, what ever though, long as you understand the process, and yes I agree, too many people answering at the same time can get frustrating

Answer 31

true I agree :) But its great to have more than one mind into thinking. Thanks for your help guys! Ill stick with my answer ^_^

Answer 32

@Jhannybean Get off your high horse, we all make mistakes.

Answer 33

Wasn't sure if it was algebraic mistakes or distributive mistakes.