p(t)=2t+3
r(t)=t2+1
s(t)=2t2−5
The polynomial functions p,r, and s are defined above. Which of the following is equivalent to 3p(t)−2r(t)−4s(t) ?
3p(t)−2r(t)−4s(t)
=3(2t+3)−2(t2+1)−4(2t2−5)
=6t+9−2t2−2−8t2+20
=−10t2+6t+27
We can try substituting an arbitrary value of t. For example, substituting t=0:
p(t)=2t+3
p(0)=2(0)+3
p(0)=3
r(t)=t2+1
r(0)=(0)2+1
r(0)=1
s(t)=2t2−5
s(0)=2(0)2−5
s(0)=−5
3p(t)−2r(t)−4s(t)
3p(0)−2r(0)−4s(0)
=3(3)−2(1)−4(−5)
=9−2+20
=27
Browsing the answer choices, only the last option evaluates to 27 when t=0.