Given #g(x) = 5x^2 - 4x# and #h(x) = 3x + 9# how do you find g(h(x))?

2 Answers
Feb 3, 2016

This means that you must plug in h into g

Explanation:

g(h(x)) = g(3x + 9)

= #5(3x + 9)^2 - 4(3x + 9)#

= #5(9x^2 + 54x + 81 ) - 12x - 36#

= #45x^2 + 270x + 405 - 12x - 36#

= #45x^2 + 258x + 369#

Hopefully this helps!

Feb 3, 2016

#g(h(x))=45x^2+258x+369#

Explanation:

#g(x)=5x^2−4x# , #h(x)=3x+9#
#g(h(x))=g(3x+9)#
#=5(3x+9)^2-4(3x+9)#
#=5(9x^2+54x+81)-12x-36#
#=45x^2+270x+405-12x-36#
#=45x^2+258x+369# => expanded form

#3(15x^2 + 86x + 123)#
#=3(15x+41)(x+3)#=> factored form