Plz help I understand

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.

Joline is solving the equation 0=x^2-5x-4 using the quadratic formula which value is the negative real number solution to her quadratic equation round to the nearest tenth if necessary

The function f(x) = 1/6(2/5)x is reflected across the y-axis to create the function g(x). which ordered pair is on g(x)? a. (-3, 4/375) b. (-2, 25/24) c. (2, 2/75) d. (3, -125/48)