Question

use an expansion formula to find the value of (21)²​

Answer 1

Answer:

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Answer 2

Step-by-step explanation:

(20+1)^2

$(a + b) {}^{2} = a {}^{2} + 2ab + b {}^{2}$

$(20 + 1) {}^{2} = 20 {}^{2} + 2 \times 20 \times 1 + 1 {}^{2}$

$= 400 + 40 + 1 = 441$