Prove, using the second derivative, that the general quadratic y= ax^2+bx+c, is:
a) always convex when a>0
b) always concave when a <0

There are three things you have to know:

So, the first derivative is

and the second derivative is

This implies that the second derivative of a parabola is constant, and of course that 2 doesn't change the sign of .

is there answer choices?

answer: $201

step-by-step explanation: to get the answer, you first get 3 nieces that he sold and multiply it by 67 and get $201, so he earned $201 selling his nieces.