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# C4 Integration by substitution question watch

1. Use the substitution u = 2x ? 5 to show that
the integral between the limits 3 and 2.5 of (4x ? 8)(2x ? 5)^7 dx
is 17/72 ?
2. What are the ? meant to be? Then I will try and help
3. the integral between the limits 3 and 2.5 of (4x - 8)(2x - 5)^7 dx
...I believe.

Putting u=2x-5 gives dx=du/2.
Find an expression for 4x-8 in terms of u.
Change the limits e.g. x=3 becomes u=2x3-5=1.

Make the substitution and integrate w.r.t u
4. (Original post by vc94)
the integral between the limits 3 and 2.5 of (4x - 8)(2x - 5)^7 dx
...I believe.

Putting u=2x-5 gives dx=du/2.
Find an expression for 4x-8 in terms of u.
Change the limits e.g. x=3 becomes u=2x3-5=1.

Make the substitution and integrate w.r.t u
TY
5. (Original post by sohinder)
TY
What does TV stand for?
6. (Original post by steve2005)
What does TV stand for?
TY, not TV, stands for Thank You
7. (Original post by sohinder)
TY
YW!
8. (Original post by vc94)
YW!
Well thanks for the negative rep, guys!
I don't know why I bother sometimes!

YW=You're Welcome

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