Posted by **susanta** on Friday, May 20, 2011 at 12:24pm.

find the value of a^3-1/8a^3 ,if a^2+1/4a^2=10

- math -
**Henry**, Friday, May 20, 2011 at 9:38pm
a^3 - a^3/8.

a^2 + a^2/4 = 10.

Multiply both sides by 4:

4a^2 + a^2 = 40,

5a^2 = 40,

a^2 = 8,

a = +-2*sqrt2.

(2*sqrt2)^3 - (2*sqrt2)^3 / 8,

8(2*sqtr2) - 8(2*sqrt2) / 8,

8(2*sqrt2) - (2*sqrt2),

7(2*sqrt2),

14*sqrt2 = 19.8.

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