Cube Numbers

Evaluate usin...

Question

Evaluate using expansion of $(a + b)^{2}$ or $(a - b)^{2}$ :
$(20.7)^{2}$ is 428.49
If true then enter $1$ and if false then enter $0$

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Solution

By using formula $(a + b)^{2} = a^{2} + 2 a b + b^{2}$
${20.7}^{2} = (20 + 0.7)^{2}$
${20.7}^{2} = (20)^{2} + {0.7}^{2} + 2 * 0.7 * 20$
${20.7}^{2} = 400 + 0.49 + 28$
${20.7}^{2} = 428.49$

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