Evaluate Q- 420 - 420-380 - 380

The correct option is A 320800420 × 420 + 380 × 380 = 420^2 + 380^2 = 1/2× ((420 + 380)^2+ (420 380)^2) =1/2×(800^2+40^2) = 1/2× (640000+1600) = 320800 ...

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Standard X

Mathematics

Arithmetic Progression

Evaluate Q. 4...

Question

Evaluate
Q. $420 \times 420 + 380 \times 380$

321600

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320800

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340800

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322800

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None of these

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Solution

The correct option is B 320800
$420 \times 420 + 380 \times 380 = 420^{2} + 380^{2} = \frac{1}{2} \times ((420 + 380)^{2} + (420 - 380)^{2})$
= $\frac{1}{2} \times (800^{2} + 40^{2})$
= $\frac{1}{2} \times (640000 + 1600) = 320800$

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Evaluate Q. 420×420+380×380

The correct option is B 320800420×420+380×380=4202+3802=12×((420+380)2+(420−380)2) =12×(8002+402) = 12×(640000+1600)=320800

Evaluate
Q. $420 \times 420 + 380 \times 380$

The correct option is B 320800
$420 \times 420 + 380 \times 380 = 420^{2} + 380^{2} = \frac{1}{2} \times ((420 + 380)^{2} + (420 - 380)^{2})$
= $\frac{1}{2} \times (800^{2} + 40^{2})$
= $\frac{1}{2} \times (640000 + 1600) = 320800$