Problem : Write out the expansion of (x + y)6.

(x + y)6 = x6 +6x5y + 15x4y2 +20x3y3 +15x2y4 +6xy5 + y6.

Problem : Write out the expansion of (x - 5)4.

(x - 5)4 = x4 -20x3 +150x2 - 500x + 625.

Problem : Write out the expansion of (2x + 7y)3.

(2x + 7y)3 = 8x3 +84x2y + 294xy2 +343y3.

Problem : Write out the expansion of (1 - x)7.

(1 - x)7 = 1 - 7x + 21x2 -35x3 +35x4 -21x5 +7x6 - x7.

Problem : Write out the expansion of (x2 +3y)4.

(x2 +3y)4 = x8 +12x6y + 54x4y2 +108x2y3 +81y4.