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Thread starter 6 years ago
#1
I am finding areas under curves and know what to do if I have something that looks like y=x^3-x^2-6x for example but I really don't know what to do with brackets. Please can someone talk me through this one?

y=x(x-1)(x+3)

What I want to do is multiply the brackets first like this:

x*x=x2,
x*3=3x,
-1*x=-x
-1*3=-3

And then multiply everything with the x at the front like this:

x*x2=x3,

x*3x=3x2,
x*-x=-x2
x*-3=-3x

Which gives me:

x3
(3x2-x2) 2x2
-3x

y=x3 +2x2 -3x

But I don't think this is right. What am I doing wrong?
1
6 years ago
#2
It is right (apart from your typo of a 2 instead of a 3 in the final line).
0
6 years ago
#3
(Original post by jami74)

y=x2 +2x2 -3x

But I don't think this is right. What am I doing wrong?
apart from changing a 3 to a 2 you are correct
0
Thread starter 6 years ago
#4
(Original post by Mr M)
It is right (apart from your typo of a 2 instead of a 3 in the final line).

(Original post by TenOfThem)
apart from changing a 3 to a 2 you are correct
Seriously? Thank-you.
Can I try another one?
0
6 years ago
#5
(Original post by jami74)
Seriously? Thank-you.
Can I try another one?
You can check your work yourself here.
1
Thread starter 6 years ago
#6
(Original post by Mr M)
You can check your work yourself here.
Thank-you Mr M
0
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