Answer:
Choice C. [tex](f-g)(x)=-x^2+17x+7[/tex]
Step-by-step explanation:
Recall that [tex]f-g[/tex] is defined by
[tex](f-g)(x)=f(x)-g(x)[/tex]
Therefore we compute
[tex](f-g)(x)=f(x)-g(x)=10x+7-x^2+7x=-x^2+17x+7[/tex]
