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Question

If \(a + b = 12\) and \(ab = 32\), then \(a^2 + b^2 = ?\)

This question was previously asked in
RRB ALP 2018 CBT 2 Fitter Question Paper (21-Jan-2019) (Shift 3)
The correct answer is
80

Calculate \(a^2 + b^2\) Using Given Sum and Product

This problem requires finding the value of \(a^2 + b^2\) given the values of \(a + b\) and \(ab\). We can use a standard algebraic identity to solve this efficiently.

Using Algebraic Identity

The relevant algebraic identity is:

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

We need to find \(a^2 + b^2\). Rearranging the identity, we get:

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

Substituting Given Values

We are given:

  • \(a + b = 12\)
  • \(ab = 32\)

Substitute these values into the rearranged formula:

\(a^2 + b^2 = (12)^2 - 2(32)\)

Step-by-Step Calculation

  1. Calculate the square of the sum: \((12)^2 = 144\).
  2. Calculate twice the product: \(2 \times 32 = 64\).
  3. Subtract the result from step 2 from the result in step 1: \(144 - 64\).

\(a^2 + b^2 = 144 - 64\)

\(a^2 + b^2 = 80\)

Therefore, the value of \(a^2 + b^2\) is 80.

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Similar Questions

  1. If a + b = 7 and ab = 12, then \(a^2 + b^2\) is equal to:

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  2. If x 2 + 4y 2 = 40, xy = 6 and x > 2y then the value of x - 2y is:

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