Question

Let f(x) = x2 + 2x - 1 and g(x) = 2x - 4.

Find 2f(x) - 3g(x)

2x^2-2x-14

I'm curious to know if I did this right?

Answer 1

re look at your calculations again, you are close but just off by last term

Answer 2

Like Juanita said, check the negative sign on your last term

Answer 3

If only you would have shown intermediate results. We could have told you where you did or didn't wander off.

\(f(x) = x^{2} + 2x - 1\)
\(g(x) = 2x - 4\)

\(2f(x) = 2x^{2} + 4x - 2\)
\(3g(x) = 6x - 12\)

\(2f(x) - 3g(x) = (2x^{2} + 4x - 2) - (6x - 12) = 2x^{2} + 4x - 2 - 6x + 12\)

\(2f(x) - 3g(x) = 2x^{2} + 4x - 6x - 2 + 12 = 2x^{2} - 2x + 10\)

If I had to guess, and I do, since you didn't show your work, you did not properly utilize the Distributive Property right here \(-(6x - 12) = -6x + 12\).

Answer 4

2x^2 + 4x -2
-6x + 12

2x^2 -2x -10

instead of -10 you add -2 and 12 as if they totaled 14

Answer 5

I was told if

f(x)-g(x) then the terms on g's side would become negative. I guess that is why I got 14

Answer 6

g(x) = 2x - 4
3g(x) = 3(2x -4 )
= 6x -12
= -1( 6x - 12)

= -6x + 12

Answer 7

Yes each sign does change...because you are multiplying by a negative 1 (subtracting)

Answer 8

When you have something like -g(x), you need to distribute the negative to the entire expression, example:
g(x) = 2x - 4

-g(x) = -(2x - 4)
but simplifies to:
-g(x) = -2x + 4