Question

If ab=5 and a-b=2 then find the value of a cube - b cube ( a3-b3 ) .

Answer 1

Answer:

38

Step-by-step explanation:

(a-b)² = a²+b²-2ab

a²+b² = (a-b)²+2ab

a²+b²=2²+2*5

a²+b²=14

a³ - b³= (a-b)(a²+b²+ab)

ab=5

a-b =2

a²+b² = 14

a³-b³ = 2(14+5) = 2*19

=38

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hope it helps:)

Answer 2

Answer:

Step-by-step explanation:

Given that,

ab=5 & a-b=2...

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

Substituting the values given......We get.....

2^3=a^3-b^3-3x5x(2)

a^3-b^3=8+30

Which implies a^3-b^3=38

I hope it helps.....