Plug in 2 for t.
=> -16*(2^2) +80*2 +3
=> -16*4 +160 +3
=> -64+163
=> 99
X^2-7=0
Add 7 to both sides.
x^2=7
Find the sqr root of 7.
It's about 2.6
I suspect 4/2 should actually be 4/3, since 4/2 = 2, while 4/3 would make V the volume of a sphere with radius r. But I'll stick with what's given:





In Mathematica, you can check this result via
D[4/2*Pi*r^3, r]
Answer:
4.9=4.2
Step-by-step explanation: