[administration]

Q. (4.2*4.2-1.9*1.9)/2.3*61 is equal to…..?

[Wonder Boy]

Here we can see  (4.2*4.2-1.9*1.9) is clearly  (4.2²-1.9²)

We know that a²-b² = (a+b)(a-b)

Hence,  (4.2²-1.9²) = (4.2+1.9)(4.2-1.9) = 6.1 x 2.3

So, (4.2*4.2-1.9*1.9) / 2.3*61 = 6.1 x 2.3 / 2.3×61 = 1/10 Ans

 

[Author]

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