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Simplify the following without multiplying :(a) 109 x 50(b) 65 x 102 (c) 102 x 21(d) 191 + 200 + 109(e) 20 x 155 |
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Answer» Answer: i)103×107 \boxed{\underline {Method 1}} Method1
(100 + 3) (100 + 7) Now, by using identity (x + a) (x + b) = x² + (a+b)*x + ab So, x = 100 , a = 3 , b = 7 = (100)² + (3+7)*100 + (3*7) = 10000 + 1000 + 21 = 11021 . \boxed{\underline {Method 2}} Method2
(110 - 7) (110 - 3) by using identity (x + a) (x + b) = x² + (a+b)*x + ab So, x = 100 , a = (-7) , b = (-3) = (110)² + { (-7) + (-3) }*110 + {(-7)*(-3)} = 12100 + (-10)*110 + 21 = 21200 - 1100 + 21 = 11021 . ➖➖➖➖➖➖➖➖➖➖ . \bf{(ii) 95 \times 96}(ii)95×96 \boxed{\underline {Method 1}} Method1
(90 + 5) (90 + 6) by using identity (x + a) (x + b) = x² + (a+b)*x + ab So, x = 90 , a = 5 , b = 6 = (90)² + (5+6)*90 + (5*6) = 8100 + 990 + 30 = 9120 . \boxed{\underline {Method 2}} Method2
(100 - 5) (100 - 4) by using identity (x + a) (x + b) = x² + (a+b)*x + ab So, x = 100 , a = (-5) , b = (-4) = (100)² + { (-5) + (-4) }*100 + 20 = 10000 + (-9)*100 + 20 = 10000 - 9000 + 20 = 10020 - 900 = 9120 . ➖➖➖➖➖➖➖➖➖➖ . \bf{(iii) 104 \times 96}(iii)104×96 \boxed{\underline {Method 1}} Method1
(100 + 4) (100 - 4) by using identity (x + a) (x + b) = x² + (a+b)*x + ab So, x = 100 , a = 4 , b = (-4) = (100)² + { 4 + (-4) }*100 + 4*(-4) = 10000 + (4 - 4)*100 - 16 = 10000 + 0*100 - 16 = 10000 - 16 = 9984 . \boxed{\underline {Method 2}} Method2
(90 + 14) (90 + 6) by using identity (x + a) (x + b) = x² + (a+b)*x + ab So, x = 90 , a = 14 , b = 6 = (90)² + (14 + 6)*90 + (14*6) = 8100 + 20*90 + 84 = 8100 + 1800 + 84 =9984 |
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