MCQ
The value of $(a+b)^2-(a-b)^2$ is:
- ✓$4ab$
- B$-4ab$
- C$2a^2 + 2b^2$
- D$2a^2 - 2b^2$
✓
Answer
Correct option: A.
$4ab$
A. $4ab$
Solution:
We have,
$(a+b)^2-(a-b)^2=a^2+b^2+2 a b-\left(a^2+b^2-2 a b\right) $
$=a^2+b^2+2 a b-a^2-b^2+2 a b=a^2-a^2+b^2-b^2+2 a b+2 a b $
$=2 a b+2 a b $
$=4 a b$
Solution:
We have,
$(a+b)^2-(a-b)^2=a^2+b^2+2 a b-\left(a^2+b^2-2 a b\right) $
$=a^2+b^2+2 a b-a^2-b^2+2 a b=a^2-a^2+b^2-b^2+2 a b+2 a b $
$=2 a b+2 a b $
$=4 a b$
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