Question

The sum of the numbers a and b is 9, whereas their product is 20. Find

(i) a3

+ b3

(ii) a2

– ab + b2​

Answer 1

Answer:

1 . 189

2. 21

Step-by-step explanation:

using simple algebraic formulae

Answer 2

Given : a+b = 9

a×b = 20

(a-b) ² = a²+b²-2ab

(9)² = a²+b² - 2(20)

81 +40 = a²-b²

121 = a²- b²

(a+b) ³ = a³+b³+3ab(a+b)

(9) ³ = a³+b³ + 3(20) (9)

729 = a³+b³ + 540

729- 540 = a³+b³

189 = a³+b³