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# Integration with limits. watch

1. I require some help with an integration question. Area between a line and a curve. I have attached the question and my working. I get an answer of 21/2 and the book says the answer is 15. I believe it’s the book that is wrong but would just like to be sure if anyone could help that would be great.
2. Here is the question and working.
Attached Images

3. (Original post by Mortifiedpenguin)
Here is the question and working.
i believe you need to use the x coordinate limits 4 and -5, rather than the y coordinates
4. The area under the x-axis is negative. You should integrate the area above and then below (this one will be negative, so take the sign into account) and add up the areas.
5. (Original post by Mortifiedpenguin)
Here is the question and working.
Unless I've officially lost the plot (the chance of such is quite high), that cannot be the graph for y=x^2+4x
Wrong shape and co-ordinates I think
6. scrap my last comment!! i think your original equation to integrate should be: x^2+x-2
7. Actually yeah that graph is ********. There's no way x^2+4x makes that graph.
8. ah yes.. that graph looks to be y=-x^2+4 !
9. you can make a triangle
find the area of the triangle and take away from the area under the curve
10. I have tried changing the equation to -x^2 + 4x that didn’t work either that gives 9/2 from what I can recall. I think the graph is wrong also. And I am using the x coordinates 😁
11. Maybe this is an impossible one.

I was playing around with my calculator because of this question and got a 19/2. Averaging them out gives a 15 but I don't see why that would be done.

On a serious note, something is very wrong with that question
12. It’s just wrong. The equation is wrong, the answer, based on the equation given is wrong. The book is so **** it’s unreal, full of wrong answers and mistakes in questions. Especially in the calculus section.

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