Question

Evaluate using identities : a
2
-b
2
= (a+b) (a-b)

40.7 x 39.3

Answer 1

Answer:

$40.7 \times 39.3 \\ \\ = (40 + 0.7)(40 - 0.7) \\ \\ = ({40})^{2} - ({0.7})^{2} \\ \\ = 1600 - 0.49 = 784$