Question

If a + b  =  12 and a3 + b3  =  468, then find the value of ab. ​

Answer 1

•Given:-

a+b=12 and a³+b³=486

•To find out:-

Value of ab=?

•Solution:-

To find the value of ab, we can use the formula or expansion for (a + b)³.

Write the formula / expansion for (a + b)3.

(a + b)³  =  a³ + 3a²b + 3ab² + b³

or

(a + b)³  =  a³ + b³ + 3ab(a + b)

Substitute 12 for (a + b) and 468 for (a³ + b³). 

(12)³  =  468 + 3(ab)(12)

Simplify.

1728  =  468 + 36ab

Subtract 468 from each side. 

1260 =  36ab

Divide each side by 36. 

35  =  ab

So, the value of ab is 35.

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