Advertisements
Advertisements
Question
If a + b = 8 and ab = 15, find a3 + b3.
Sum
Advertisements
Solution
Here, a + b = 8, ab = 15
Using the identity,
a3 + b3 = (a + b)3 − 3ab (a + b)
= (8)3 − 3(15)(8)
= 512 − 3(120)
= 512 − 360
∴ a3 + b3 = 152
shaalaa.com
Application of Formulae
Is there an error in this question or solution?
Chapter 3: Expansions - EXERCISE B [Page 35]
RELATED QUESTIONS
If a+b=5 and ab = 6, find a2 + b2
If a – b = 6 and ab = 16, find a2 + b2
If a2 + b2 = 29 and ab = 10, find : a − b
If `"a" - 1/"a"=4`, find : `"a"^2+1/"a"^2`
Find : a + b + c, if a2 + b2 + c2 = 83 and ab + bc + ca = 71.
If `3"x"+1/(3"x")=3`, find : `9"x"^2+1/(9"x"^2)`
If a2 + b2 = 41 and ab = 4, find : a – b
If a + b + c = 9 and ab + bc + ca = 15, find: a2 + b2 + c2.
If 3x + 2y = 9 and xy = 3, find : 27x3 + 8y3.
The difference between the two numbers is 5 and their products are 14. Find the difference between their cubes.
