Question

4. Using identity (a + b)(a - b) = a? - 62, evaluate the following:
(i) 14.7 x 15.3

(ii)34/5 × 46/ 5
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Answer 1

Answer:

1) 14.7×15.3

=(15-0.3)(15+0.3)

=(15)²-(0.3)²

=225×0.09

=20.25

2)34/5×46/5

Answer 2

Step-by-step explanation:

i.) 14.7 x 15.3

( 15 - 0.3 ) x ( 15 + 0.3 )

(a + b)(a - b) = a² - b²

(15)² - (0.3)²

225 - 0.009

224.991

ii.)i.) 34/5 x 46/5

( $\frac{40}{5} - \frac{6}{5}$ ) x ( $\frac{40}{5} + \frac{6}{5}$ )

(a + b)(a - b) = a² - b²

($\frac{40}{5}$)² - ($\frac{6}{5}$)²

1600/25 - 36/25

1600 - 36/25

1564/25

62.56