Find the coefficient of x^3 in (2x-3)^7

Answer 1

Ans is -

22680

rewrite the equation (2x-3)^3 * (2x-3)^2 * (2x-3)^2

(2x-3)^3 will be

8x^3-36x^2+54x-27 -----(1)

and (2x-3)^2 *(2x-3)^2 will be

16x^4-96x^3+216x^2-216x+81------(2)

now solve for x^3 coff. olny by multiplying both the equations

we get ....

.....648 x^3 + 7776 x^3 + 11664 x^3 + 2592 x^3

ie. 22680 x^3