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SSC CPO Tier 1 Exam 10 Dec 2025 Shift 1

Section: Quantitative Aptitude

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Question : 126 of 200

Marks: +1, -0

If

a ^ 2 + b ^ 2 = 100

and a - b = 4 find the value of ab.

28
32
42
54

Solution:

Concept:

Use the identity

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

to relate the given values.

Explanation:

First, square the given difference:

(a - b)^2 = 4^2 = 16

.

We know

a^2 + b^2 = 100

. Substitute into the identity:

16 = 100 - 2ab

.

Rearrange:

2ab = 100 - 16 = 84

.

Divide by 2:

ab = 42

.

Answer:

42 (Option C)

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