Find the value of:
(i) (82)2 – (18)2
(ii) (128)2 – (72)2
(iii) 197 × 203
(iv) 
(v) (14.7 × 15.3)
(vi) 
(i) Given,
(82)2 – (18)2
By using (a – b)(a + b) = a2 – b2
= (82 – 18)(82 + 18)
= (64)(100)
= 6400
(ii) (128)2 – (72)2
By using (a – b)(a + b) = a2 – b2
= (128 – 72)(128 + 72)
= (56)(200)
=11200
(iii) 197 × 203
By converting the given number into the form of formula we get,
= (200 – 3)(200 + 3)
= (200)2 –(3)2
= 40000 – 9
= 39991
(iv) Given,
By using the formula (a – b)(a + b) = a2 – b2
We get;
= 300
(v) (14.7 × 15.3)
By using (a – b)(a + b) = a2 – b2
We get;
= (15 – 0.3)(15 + 0.3)
= (15)2 – (0.3)2
= 225 – 0.09
= 224.91
(vi) (8.63)2 – (1.37)2
By using (a – b)(a + b) = a2 – b2
We get;
= (8.63 – 1.37)(8.63 + 1.37)
= (7.26)(10)
= 72.6
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