Van someone me answer these questions

Why do interests rates on loans to be lower in a weak economy than in a strong one

Which expression do you get when you eliminate the negative exponents of 4a^2 b^216a^-3 b

Estimate the area under the curve f(x) = 16 - x^2 from x = 0 to x = 3 by using three inscribed (under the curve) rectangles. answer to the nearest integer.