The value of 21² is?

220+221

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219+220

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218+219

No worries! We‘ve got your back. Try BYJU‘S free classes today!

217+218

No worries! We‘ve got your back. Try BYJU‘S free classes today!

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Solution

The correct option is A
220+221

$21^{2}$ = $(20 + 1)^{2}$
Now we will use the algebraic identity $(a + b)^{2} = a^{2} + 2 a b + b^{2}$
= ((20)² + 2x20x1 + (1)²)
= (400 + 40 + 1)
= 441

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