What is the value of (22 + 42 + 62 + … + 402) – (12 + 32 + 52 + … + 392)?

Options
- 410
- 820
- 800
- 780

CORRECT ANSWER : 820

Discussion Board
Its Easy

difference of 2 consecutive squares are equal to sum of those numbers. Eg: 23^2-22^2= 23+22

thus u can take the question as 2^2-1^2 + 4^2-3^....... 40^2-39^. will give as 3, 7, 11,15.......79. Its AP. so, further its easy

Nikhil 07-3-2018 06:01 AM

Quant

Plz provide explanation

XYZ 03-3-2018 03:03 AM

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