Hey guys, I'm having trouble with this problem, maybe you can help me out?

Letf(x) = 72 +x-x2 andg(x) =x2 - 9x.

Find the area between the graphs offandgover [1, 6].

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- Sep 21st 2010, 08:04 PMbigdanTrouble finding area between graphs
Hey guys, I'm having trouble with this problem, maybe you can help me out?

Let*f*(*x*) = 72 +*x*-*x*2 and*g*(*x*) =*x*2 - 9*x*.

Find the area between the graphs of*f*and*g*over [1, 6]. - Sep 21st 2010, 08:18 PMTruthbetold
What have you tried so far?

I'd work with the formula: integral of g(x) - f(x) - Sep 21st 2010, 08:22 PMbigdan
I tried that brother! Except the graphs cross at 4.3245, so, from what I think I've learned haha ;), I split it into two parts, integrating from 0 to 4.3245 and 4.3245 to 6. f(x)-g(x) for the first part because f is higher than g, then g(x)-f(x) for the second part, because g was higher than f. Where am I going wrong?

- Sep 21st 2010, 08:54 PMEducated
It would help if you posted your working.

Quote:

the graphs cross at 4.3245

Doing f(x) - g(x) seems more correct to me. f(x) should be higher. - Sep 22nd 2010, 02:21 AMHallsofIvy
You need to solve 72 + x - x^2= x^2 - 9x to find the points at which the graphs cross. If you integrate with respect to x, you can do it with only one integration.