2x+1/x=4
then find
x^3+1/8×^3
Answers
Answer is 76
Step-by-step explanation:
Solution:
We know the identity equation:
\mathbf{(A-B)^{3}=A^{3}-B^{3} -3A\times B(A-B)}(A−B)3=A3−B3−3A×B(A−B) ...2)
Taking cube of both side of equation 1):
\mathbf{ ( 2x-\dfrac{1}{2x} )^{3}=4^{3}}(2x−2x1)3=43
L.H.S of above equation can be solved by with help of equation 2):
\mathbf{(2x)^{3}- ( \dfrac{1}{2x} )^{3} -3\times 2x\times \dfrac{1}{2x}(2x-\dfrac{1}{2x})=64}(2x)3−(2x1)3−3×2x×2x1(2x−2x1)=64
\mathbf{8x^{3}-\dfrac{1}{8x^{3}} -3\times (2x-\dfrac{1}{2x})=64}8x3−8x31−3×(2x−2x1)=64 ...3)
With help of equation 1):
\mathbf{8x^{3}-\dfrac{1}{8x^{3}} -3\times 4=64}8x3−8x31−3×4=64
\mathbf{8x^{3}-\dfrac{1}{8x^{3}} -12=64}8x3−8x31−12=64
\mathbf{8x^{3}-\dfrac{1}{8x^{3}} =76}8x3−8x31=76
This is answer.Means
\mathbf{Value\ of\ 8x^{3}-\dfrac{1}{8x^{3}} \ is\ 76}Value of 8x3−8x31 is 76
Step-by-step explanation:
ans is 2.it is the 100% correct ans.
