Question

Evaluate (f-g)(3t) for f(x)=x²+1 and g(x)=x-4

Answer 1

$(f-g)(3t) \\ \\ f(x)-g(x) \\ \\ f(3t)-g(3t) \\ \\ ((3t)^2+1)-((3t)-4) \\ \\ 9t^2+1-3t+4 \\ \\ 9t^2-3t+5$

Answer 2

f(x)=x²+1

g(x)=x-4

------------

f(x)-g(x)

=x²+1-(x-4)

=x²+1-x+4

=x²-x+5

------------

Therefore:

(f-g)(3t)

=(3t)²-3t+5

=3²t²-3t+5

=9t²-3t+5