Question

If x^2 +1/4x^2=8, find x^3+1/8x^3​

Answer 1

Step-by-step explanation:

x^2+1/4x^2+1=9

(x+1/2x)^2=9

(x+1/2x)=3 or -3

(x+1/2x)^3=27(for 3)

x^3+1/8x^3+3/2(x+1/2x)=27

x^3+1/8x^3=27-9/2=45/2

(x+1/2x)^3=-27

x^3+1/8x^3+3/2(x+1/2x)=-27

x^3+1/8x^3=-27+9/2=-45/2