kelsey1 2 years ago f(x)=-x^2+5x+7 Find f(3a-4)

1. tacamry

so wat am pose to be doing?

2. Stephchen

substitute 3a-4 to all the x in the equation

3. kelsey1

yes I know, but I'm not sure how to do that like can you show me the steps

4. Hero

f(x)=-x^2+5x+7 f(3a-4) = -(3a-4)^2 + 5(3a -4) + 7 Simplify the expression

5. Stephchen

|dw:1354855276611:dw| For the first term

6. Hero

Bro, the first term is negative

7. Stephchen

However there is a negative sign in fron of x so you have to multiply the first term with negative one.

8. Stephchen

Hero buddy, patience... lol

9. Hero

But anyway, the difficult part is done. Let the person finish it themselves.

10. Stephchen

I assume you'll have the idea to do the next ones from here on?

11. kelsey1

I know how to do foil and all the math yet are you solving for x or leaving it as a quadratic?

12. Hero

Nothing nowhere says to solve for x. In fact, when I posted the hint I gave you. I left a comment below saying to "simplify the expression". How did you interpret "solve for x" from that?

13. Stephchen

x becomes a, so x is out of the picture. if your asked to simplify the expression then I guess all you have to do is the equation hero did setup for you.

14. Stephchen

you're*

15. kelsey1

Well I meant "a" and my problem was that I thought I was solving for "a".

16. Stephchen

then I guess you're all set :)

17. Hero

@kelsey1, will you please just simplify the expression and let us know what you get?

18. kelsey1

9a^2-9a+3