Question

$find \: (70 {}^{2} { - 69}^{2}) + (68 {}^{2} { - 67 {}^{} }^{2}) + (66 {}^{2} { - 65}^{2}) + (2 {}^{2} { - 1 {}^{} }^{2})$
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Answer 1

Answer:

2485

Step-by-step explanation:

a^2-b^2=(a+b)(a-b)

applying this

(70+69)(1)+(68+67)(1)+.....+(2+1)(1)

1+2+3+4+....+70

sum of n natural no=n(n+1)/2

70(71)/2

35(71)

2485

hope it helps u