Home
Class 8
MATHS
If x^2+1/x^2=7 and x!=0: find the value ...

If `x^2+1/x^2=7` and `x!=0`: find the value of `7x^3+8x-7/x^3-8/x`

Text Solution

Verified by Experts

`x^2+1/x^2=7`
`(x-1/x)^2=x^2+1/x^2-2`
`(x-1/x)^2=7-2=5`
`x-1/x=sqrt5`
`7x^3+8x-7/x^3-8/x`
`7(x^3-1/x^3)+8(x-1/x)`
`7((x-1/x)(x^2+1/x^2+1))+8(x-1/x)`
`7((sqrt5(7+1))+8(sqrt5)`
...
Promotional Banner

Similar Questions

Explore conceptually related problems

If x^(2) + (1)/(x^(2))= 7 and x ne 0 , find the value of : 7x^(3) + 8x- (7)/(x^(3))- (8)/(x)

If x=sqrt(3) find the value of 2x^2-8x+7.

If x=(sqrt3+1)/2 find the value of 4x^3+2x^2-8x+7

If x=(sqrt(3)+1)/2, find the value of 4x^3+2x^2-8x+7.

If a is a root of x^(2) - 3x-5=0 find the value of a^(4) - 2a^(3) - 7a^(2) -8a

If x=(sqrt(3)+1)/(2), find the value of 4x^(3)+2x^(2)-8x+7

If the x= 8+ 3sqrt7 , find the value of x^(2) + (1)/(x^(2)) .

If the mean of 2,3, x ,7 ,8 is x, then find the value of x .