Posted by **JOSHI ** on Saturday, June 23, 2012 at 3:18am.

write expansions:

1) (4/3x+3/4y)^3

- maths -
**Reiny**, Saturday, June 23, 2012 at 8:50am
in general

(a+b)^3 = a^3 + 3a^2 b + 3a b^2 + b^3

then ...

(4/3x+3/4y)^3

= (4/3)^3 x^3 + 3(4/3)^2 x^2 (3/4)y + 3(4/3)x (3/4)^2 y^2 + (3/4)^3 y^3

= 64x^3/27 + 144x^2 y/36 + 108xy^2/48 + 27y^3/64

= 64x^3/27 + 4x^2y + 9xy^2/4 + 27y^3/64

testing by letting x=1, y=1

(4/3 + 3/4)^3 = appr 9.0422..

my expression at the end = .0422..

I assume you meant it the way you typed it

if you meant

( 4/(3x) + 3/(4x) )^3 it would totally change the answer.

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