Question
Using the identites of algebriac expression , find the following :
(i) 403×397
(ii) 8.22
(iii) 9.7×9.8
(iv) 22.92−7.12 [4 MARKS]
Answer: Option A
:
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Application: 1 Mark each
(i) 403×397
=(400+3)(400−3)
=[(400)2−(3)2]
=160000−9
=159991
(ii) 8.22
=(8+0.2)2
=(8)2+(0.2)2+2(8)(0.2)
=64+0.04+3.2
=67.24
(iii) 9.7×9.8
=(9+0.7)(9+0.8)
=(9)2+(0.7+0.8)9+(0.7)(0.8)
=81+13.5+0.56
=95.06
(iv) 22.92−7.12
=(22.9+7.1)(22.9−7.1)
=(30)(15.8)
=474
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