Question

if a+b=15 and a^2 + b^2=113, then find the value a^3+b^3.​

Answer 1

Answer:

855

Step-by-step explanation:

a²+ b²

= (a+b)² - 2ab

= 15²- 2ab = 113

= 225-113=2ab

= ab=56

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a³+b³= ( a+ b)³ - 3ab(a+b)

= 15³ - 3(56)(15)

= 855

Answer 2

Answer:

1305

Step-by-step explanation:

(a+b)^2 = a^2 + b^2 +2ab

15^2 = 113 +2ab

225 + 113+2ab

2ab = 225 - 113

ab = 112/2 = 56

a^3 + b^3 = (a+b)^3 - 3ab(a+b)

               = 15^3 - 3(56)(15)

                = 3375 - 2520

                = 855