Question

simplify (πd²/4)-(π[d+1]²/4)

Answer 1

Factor pi/4.
Then, it is a difference of squares.
Simplify.

Answer 2

wouldn't it be π/4 (d^2-d^2+1)?

Answer 3

No. It is pi/4(d^2 - (d+1)^2)

Answer 4

so how do i solve that? :S

Answer 5

a^2 - b^2 = (a-b)(a+b)

Answer 6

In the above, a = d, b = d+1.

Answer 7

i got π(2d-1)/4 .... is that right? because the back of my book says the answer is π(2d+1)/4

Answer 8

pi/4 (d^2 - (d+1)^2) = pi/4 (d + d + 1)(d - (d-1)) = pi/4 (2d+1)(d-d+1) = pi/4 (2d+1)

Answer 9

how is it pi/4 (d + d + 1)(d - (d-1)) ?

Answer 10

Forget pi/4 since that is already factored out.

Focus on (d^2 - (d+1)^2). Like I said, a^2 - b^2 = (a+b)(a-b).
Here, you have d^2 - (d+1)^2 = (d+d+1)(d-(d+1))

Answer 11

OOOOOH ! im subtracting it.. instead of multiplying (x my bad

Answer 12

wait but i still get 2d-1
:S

Answer 13

Actually, you get -(2d+1)

Answer 14

): it says the answer is pi/4 2d+1

Answer 15

I see the answer as the same, but with a minus sign. But, may be missing something.

Answer 16

oh well i'll just keep it like this for now and ask my teacher tomorrow. thanks