Advertisements
Advertisements
Question
If `"r" - (1)/"r" = 4`; find : `"r"^3 - (1)/"r"^3`
Sum
Solution
`("r" - 1/"r")^3`
=`"r"^3 - (1)/"r"^3 - 3("r" - 1/"r")`
⇒ (4)3 = `"r"^3 - 1/"r"^3 - 3(4)`
⇒ `"r"^3 - (1)/"r"^3`
= 64 + 12
= 76.
shaalaa.com
Is there an error in this question or solution?
APPEARS IN
RELATED QUESTIONS
Expand.
`(x + 1/x)^3`
Expand.
`(2m + 1/5)^3`
Find the cube of : `2a + 1/(2a)` ( a ≠ 0 )
Expand : (3x + 5y + 2z) (3x - 5y + 2z)
If a ≠ 0 and `a- 1/a` = 3 ; Find :
`a^3 - 1/a^3`
If `9"a"^2 + (1)/(9"a"^2) = 23`; find the value of `27"a"^3 + (1)/(27"a"^3)`
If `x^2 + (1)/x^2 = 18`; find : `x^3 - (1)/x^3`
Evaluate the following :
(3.29)3 + (6.71)3
If `x^2 + 1/x^2` = 23, then find the value of `x + 1/x` and `x^3 + 1/x^3`
Expand (3 + m)3
