Question

using suitable identites 20.5×19.5​

Answer 1

Question:–

Use a suitable identity to solve the following:-

20.5 $\times$ 19.5

____________________________

Answer:–

==>20.5 $\times$ 19.5

We can also write this as:-

==>(20+0.5)(20-0.5)

We can use the identity---

(a+b)(a-b)=a²-b²

In this question---a=20, b=0.5

Now using this identity we have:-

(20+0.5)(20-0.5) =(20)²-(0.5)²

==>(20)²-(0.5)²

==>400-0.25

==>399.75

★Hence the required answer is 399.75 and the identity used is (a+b)(a-b)=a²-b².

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