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
Answers
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
.
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.
\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
.
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.
\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
Answer:
hope it helps you thanks
