binomial theorem?

Question

write down the expansion by binomial theorem of [3x-y/2]^4. By giving x and y suitable values ,deduce the value of (29.5)^4 .

Answer 1

(81)x^4 -(54)(x^3)(y) +(27/2)(x^2)(y^2) -(3/2)(x)(y^3) +(1/16)(y^4)

substitute x = 10 and y = 1 in the expansion

Answer 2

[3x - y/2]^4 =
(3x)^4 - (4)(3x)^3(y/2) + (6)(3x)^2(y/2)^2 - (4)(3x)(y/2)^3 + (y/2)^4 =

81x^4 - 54x^3y + (27/2x^2y^2 - (3/2)xy^3 + (1/16)y^4

29.5 = 3*10 - 1/2

81*10^4 - 54*10^3 + 27*50 - 15 + 1/16 =
810000 - 54000 + 1350 - 15 + 0.0625 =
757335.0625