Advertisements
Advertisements
Question
Find : `"a"^3+1/"a"^3`, if `"a" +1/"a"=5`.
Sum
Advertisements
Solution
`"a" +1/"a"=5`
`⇒("a"+1/"a")^3=(5)^3`
`⇒"a"^3+1/"a"^3+3"a"xx1/"a"("a"+1/"a")=125`
`⇒"a"^3+1/"a"^3+3(5)=125` ........`["a"+1/"a"=5]`
`⇒"a"^3+1/"a"^3+15=125`
`⇒"a"^3+1/"a"^3=125-15`
`⇒"a"^3+1/"a"^3=110`
shaalaa.com
Application of Formulae
Is there an error in this question or solution?
APPEARS IN
RELATED QUESTIONS
If a+b=5 and ab = 6, find a2 + b2
If a – b = 6 and ab = 16, find a2 + b2
If `"a"^2+ 1/"a"^2=23`, find : `"a" +1/"a"`
If a + b + c = 10 and a2 + b2 + c2 = 38, find : ab + bc + ca
Find : a + b + c, if a2 + b2 + c2 = 83 and ab + bc + ca = 71.
If a – b = 3 and ab = 10, find : a3 – b3.
Find:
`a^3-1/a^3`, if `a -1/a = 4`.
If a + b + c = 9 and ab + bc + ca = 15, find: a2 + b2 + c2.
If a + b + c = 11 and a2 + b2 + c2 = 81, find : ab + bc + ca.
If 5x – 4y = 7 and xy = 8, find : 125x3 – 64y3.
