Finddy/dxandd2y/dx2.x = t2 + 7, y = t2 + 5tdydx = d2ydx2 = for which values of t is the curve concave upward? (enter your answer using interval notation.)=

By the chain rule,

We have

Notice that this derivative is a function of . Let . Then by the chain rule,

We have

The curve is concave upward wherever the second derivative is positive. This happens whenever , or .

the 8 in 8,420 is in the thousands place so it's value is 8 thousand.

the 8 in 6,870 is in the hundreds place so it's value is 8 hundred.

divide 8000 by 800 to find the answer:

8000 / 800 = 10

the 8 in 8,420 is 10 times greater than the 8 in 6,870