If a + b = 40 and a² + b² = 872, then a³ + b³ = ?

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30 May 2022 Number System

If a + b = 40 and a² + b² = 872, then a³ + b³ = ?

OPtion

1) 8640
2) 2880
3) 11520
4) 10160
5) 28000
6) 20320
7) 15240
8) 40720
9) 19000
10) None of these

Solution

Given, a + b = 40 and a² + b² = 872
(a+b)² = a² + b² + 2ab
40² = 872 + 2ab
⇒ ab = 364
Now, a³ + b³ = (a+b) (a² + b² - ab) = 40*(872 -364) = 20320
Correct Option 6)

Correct Option: 6 Best Solution (1)