Answer:
20) [tex]11x^2+13x+6[/tex]
21) [tex]-x^2+5x-3[/tex]
Step-by-step explanation:
20)
[tex]2f(x)+3g(x)=2(4x^2-x+3)+3(x^2+5x)=8x^2-2x+6+3x^2+15x=\boxed{11x^2+13x+6}[/tex]
21)
[tex]f(x)-g(x)=(3x^2-2x+5)-(4x^2-7x+8)=3x^2-4x^2-2x+7x+5-8=\boxed{-x^2+5x-3}[/tex]
And we're done!
