Question
Evaluate the following using identities:
$(399)^2$
$(399)^2$
✓
Answer
We have,
$399^2=(400-1)^2$
$=(400)^2+(1)^2-2 \times 400 \times 1\left[(a-b)^2=a^2+b^2-2 a b\right]$
Where, $a=400$ and $b=1$
$=160000+1-8000$
$=159201$
Therefore, $(399)^2=159201$
$399^2=(400-1)^2$
$=(400)^2+(1)^2-2 \times 400 \times 1\left[(a-b)^2=a^2+b^2-2 a b\right]$
Where, $a=400$ and $b=1$
$=160000+1-8000$
$=159201$
Therefore, $(399)^2=159201$
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