Ex 8.2, 3 - Class 11

Transcript

Ex 8.2, 3 Write the general term in the expansion of (x2 – y)6 We know that General term of expansion (a + b)n is Tr+1 = nCr an–r br For (x2 – y)6 Putting n = 6 , a = x2 , b = –y Tr+1 = 6Cr (x2)6–r (–y)r = ﷐6!﷮𝑟!﷐6 −𝑟﷯!﷯ . (x)2(6 – r) . (–1)r . (y)r = ﷐6!﷮𝑟!﷐6 −𝑟﷯!﷯ . (x)12 – 2r . (–1)r . (y)r =(–1)r ﷐6!﷮𝑟!﷐6 −𝑟﷯!﷯ . x12 – 2r . yr