Hello,
f(π/2)=4*sin(π/2)-2=4*1-2=2
f(0)=4*sin(0)-2=0-2=-2
rate=(2+2)/(π/2-0)=8/π
Answer D
Personally i think that if you use the pi symbol it would be more accurate because on a calculator there is an pi symbol √ which is the same it will give you an answer closer to an whole number.
1 root.
The reasoning is the same for your other question except x is positive this time round giving x=8 as your only root.
A = LW for W
A/L = LW/L = A/L=W
/ = fraction bars but i couldn't use fraction bars
hopefully this helped ! :)