If a – b = 7 and a2 + b2 = 85, then find the value of a3
– b
3 ...... bhai koi easy method me samjha do
Answers
Answered by
1
a - b = 7 (given)
a = b + 7
a² + b² = 85
(b + 7)² + b² = 85
b² + 49 + 14b + b² = 85
2b² + 14b - 36 = 0
b² + 7b - 18 = 0
b² + 9b - 2b - 18 = 0
b( b + 9) - 2 ( b + 9) = 0
(b - 2)(b + 9) = 0
b = 2
b = -9
b = 2
a = b + 7
a = 9
a³ - b³= 9³ - 2³
= 729 - 8
= 721
Similar questions