Question

Use the Binomial Theorem to find the coefficient of the x^2 y^6 term in the expansion of (5x-2y)^8.

Answer 1

Hint: Compute 8 C 6

Answer 2

Then multiply this by (5^2)*(2^6) = 1600

Answer 3

?????

Answer 4

Do you know how to evaluate 8 C 6?

Answer 5

no >.>

Answer 6

n C r = (n!)/(r!(n-r)!)


8 C 6 = (8!)/(6!*(8-6)!)


8 C 6 = (8!)/(6!*2!)


8 C 6 = (8*7*6!)/(6!*2!)


8 C 6 = (8*7)/(2!)


8 C 6 = (8*7)/(2*1)


8 C 6 = (56)/(2)


8 C 6 = 28

Answer 7

Multiply that result with 1600 to get 28*1600 = 44800


So the coefficient of the x^2y^6 term is 44800

Answer 8

oh