Thread: help algebra 2 functions

f(x) 2x+1, g(x)=2x^2+x

determine (gf)(3)

ok so i dont know where to go since this is an online class

g(f(3)?
g(2(3)+1 = 7?
g(7)?
so confused someone please do this step by step i especially dont know how to do these when there are exponents like the 2x^2

Originally Posted by siberianfog

f(x) 2x+1, g(x)=2x^2+x

determine (gf)(3)

ok so i dont know where to go since this is an online class

g(f(3)?
g(2(3)+1 = 7?
g(7)?
so confused someone please do this step by step i especially dont know how to do these when there are exponents like the 2x^2

wow thank you i have been getting them done fast now, 1 more pleasE? its very very very appreciated.

f(x) 2x+1, g(x)=2x^2+x
determine (fg)(x+1)

Originally Posted by siberianfog

wow thank you i have been getting them done fast now, 1 more pleasE? its very very very appreciated.

f(x) 2x+1, g(x)=2x^2+x
determine (fg)(x+1)

... you finish it.

2(x^2+1)+(x+1)
2x^2+2+x+1
2x^2+3+x

I GOT
2(2x^2 + 3 + x) = 4x^2 + 6 + x

but the book says thats wrong

4x^2+10x+7? dont know where you get that

2(x^2+1)+(x+1)

... note that

where do i go wrong?

2(x^2 + 1) + (x+1)
2x^2 + 2 + x + 1
2x^2 + 3 + x

2(2x^2 + 3x + x)
4x^2 + 6x + 2x + 1
4x^2 + 8x + 1

once again ...

specifically ... does not equal


I recommend you research how to square a binomial.

Thank you