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If the sum of squares of two numbers is 9797, then which one of the following cannot be their product?

Solution

✅ Correct Option: 1

Let the two numbers be aa and bb.

Given: a2+b2=97a^2 + b^2 = 97

We need to find which value cannot be their product abab.


To find the range of possible values for abab, we use the identity:

(a−b)2=a2+b2−2ab(a - b)^2 = a^2 + b^2 - 2ab

Since (a−b)2≥0(a - b)^2 \geq 0 for any real numbers, we have:

a2+b2−2ab≥0a^2 + b^2 - 2ab \geq 0

Substituting a2+b2=97a^2 + b^2 = 97:

97−2ab≥097 - 2ab \geq 0

97≥2ab97 \geq 2ab

ab≤972=48.5ab \leq \dfrac{97}{2} = 48.5


The maximum value ab=48.5ab = 48.5 is achieved when (a−b)2=0(a - b)^2 = 0

The product abab must satisfy ab≤48.5ab \leq 48.5.

Therefore, any value greater than 48.548.5 cannot be their product. Only such value from the options is 6464

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