Evaluate the following by using factors:

Evaluate the following by using factors:

(i) (979)² – (21)²

(ii) (99.9)² – (0.1)²

Answer :

(i) (979)² – (21)²

We know that

= (979 + 21) (979 – 21)

So we get

= 1000 ×958

= 958000

(ii) (99.9)² – (0.1)²

We know that

= (99.9 + 0.1) (99.9 – 0.1)

So we get

= 100 × 99.8

= 9980

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