SOLUTION: (It don't have in textbook but teacher gives me worksheet) Can you help me solve this problem: June factored the polynomial c^9-d^12 into (c^3+d^4)(c^6-c^3*d^4+d^8). Is sh

Algebra ->  Polynomials-and-rational-expressions -> SOLUTION: (It don't have in textbook but teacher gives me worksheet) Can you help me solve this problem: June factored the polynomial c^9-d^12 into (c^3+d^4)(c^6-c^3*d^4+d^8). Is sh      Log On


   



Question 167092: (It don't have in textbook but teacher gives me worksheet)
Can you help me solve this problem:
June factored the polynomial c^9-d^12 into (c^3+d^4)(c^6-c^3*d^4+d^8).
Is she correct? How do u know?
MANY THANKS

Found 2 solutions by checkley77, Earlsdon:
Answer by checkley77(12844) About Me  (Show Source):
You can put this solution on YOUR website!
She is correct.
Proof:
c^6-c^3*d^4+d^8
c^3+d^4 multiply
----------------------------
c^9-c^6d^4+c^3d^8+c^6d^4-c^3d^8+d^12
c^9+d^12 answer.

Answer by Earlsdon(6294) About Me  (Show Source):
You can put this solution on YOUR website!
June is not correct!
How do we know?
One way to prove this is to multiply the two factors, using FOIL, to see if you arrive at the given polynomial.
Simplifying.
c%5E9%2Bd%5E12 and this is not the same as the given polynomial of c%5E9-d%5E12
Another way is to recognize the given polynomial as the difference of two cubes:
c%5E9-d%5E12+=+%28c%5E3%29%5E3+-+%28d%5E4%29%5E3 and the difference of two cubes is factored thus:
A%5E3-B%5E3+=+%28A-B%29%28A%5E2%2BAB%2BB%5E2%29 where: A+=+c%5E3 and B+=+d%5E4
%28c%5E3%29%5E3+-+%28d%5E4%29%5E3+=+%28c%5E3-d%5E4%29%28c%5E6%2Bc%5E3%2Ad%5E4%2Bd%5E8%29 and this is not what June got!