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Algebra problem?
I'm sure it isn't too hard, but I'm not sure how to do this:
f(x) = 2x^2 + 3x - 4, g(x) = 2x - 1
Find f(g(x))
I can usually do these, but the trinomial throws me off and my teacher doesn't go over our homework so he didn't explain it to us.
Wow, that's so simple, why couldn't my teacher just explain it or even do an example like that? Whatever, thanks everyone.
7 Answers
- gudspelingLv 71 decade agoFavorite Answer
f(x) = 2x² + 3x - 4, g(x) = 2x - 1
f(g(x)) = 2(2x-1)² + 3(2x-1) - 4
= 2(4x² - 4x + 1) + 6x - 3 - 4
= 8x² - 8x + 2 + 6x - 7
= 8x² - 2x - 5
- frankLv 71 decade ago
f(x) = 2x^2 +3x -4
g(x) = 2x -1
fog(x) = f(g(x)) = f(2x -1) = 2(2x -1)^2 +3(2x -1) -4
= 2(4x^2 -4x +1) + 6x -3 -4
= 8x^2 -8x +2 +6x -3 -4
= 8x^2 -2x -5
- 1 decade ago
Rewrite f(x) with (2x - 1) in the place of each x and then simplify.
f(g(x)) = 2(2x - 1)^2 + 3(2x - 1) - 4
etc.
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- Anonymous1 decade ago
i have no idea how to do it cause we haven't learned it but if ur teacher isn't explianing to u, try asking him when everyone is out of the classroom, thats what i do cause i don't like to raise my hand in classes, or maybe tlk to him after school
- 1 decade ago
okay, you plug g(x) in everywhere you see x in f(x) so:
f(x) = 2x^2 + 3x - 4, g(x) = 2x - 1
f(g(x))=2(2x-1)^2+3(2x-1)-4
f(g(x))=2(2x-1)(2x-1)+6x-3-4
f(g(x))=(4x-2)(2x-1)+6x-7
f(g(x))=8x^2-4x-4x+2+6x-7
f(g(x))=8x^2-2x-5
