# Math Help - Help in integration

1. ## Help in integration

Hi, I could not figure out two questions in my homework. The first problem deals with a piecewise function.

9
g(x)dx, where g(x)={1, x> 0 and x^3, 1 < x < 4 and sqrt x, 4 < x < 9
0

also,

Find the area below the interval [-2, -1], but above the curve y=x^3

Does this just mean
-1
(x^3)dx
-2

??

2. Originally Posted by kn336a
Hi, I could not figure out two questions in my homework. The first problem deals with a piecewise function.

9
g(x)dx, where g(x)={1, x> 0 and x^3, 1 < x < 4 and sqrt x, 4 < x < 9
0

also,

Find the area below the interval [-2, -1], but above the curve y=x^3

Does this just mean
-1
(x^3)dx
-2

??
For Q1 try

$I_n=\int_0^1 1 dx + \int_1^4 x^3 dx + \int_4^9 \sqrt{x} dx$

For Q2 you are correct.

3. Ok hi

I attach my answer the second question you just should multiply the answer by -1

Attachment 11481

Attachment 11482

4. I was late sorry

5. Thanks guys! I got 929/12 for the first one or roughly 77.4167

the second one I got -15/4

is this right? I hope so!

6. you answer is correct but the second I think you should take the absolute value cuz it is area and the area positive value

7. sorry, I'm a little confused. So do I just add an absolute value sign after the integration sign, then calculate?

I've gotten negative numbers for some of my integration problems and didn't get marked wrong. Is it because it says "but above the curve y=x^3?"

I thought that just meant the area between the interval and the curve. Thanks!