ICSE Class X Math 2015 Solved Paper | Question 5

ICSE Class X Math 2015 Solved Paper

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Question : 5

Total: 52

If A=[

3	x
0	1

] and B=[

9	16
0	−y

], find x and y when A2=B.

Solution:

‌‌ Given : ‌A=[

3	x
0	1

]‌ and ‌B=[

9	16
0	−y

]
‌A2=B
‌[

3	x
0	1

][

3	x
0	1

] =[

9	16
0	−y

]
‌[

3×3+x×0	3×x+x×1
0×3+1×0	0×x+1×1

]=[

9	16
0	−y

]
‌[

9	4x
0	1

]=[

9	16
0	−y

]
By equality of matrices,
4x‌=16‌‌ and ‌‌1‌=−y
x‌=4‌‌ and ‌‌y‌=−1

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