answer this mcq step by step
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here is your answer 232
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1. Given,
3x + 7y = 20
xy = 4
To find:
9x² + 49y²
Solution:
9x² + 49y²
= (3x)² + (7y)²
= (3x+7y)² - 2*3x*7y [∴ a²- b² = (a + b²) - 2ab]
= 20² - 2*21xy
= 400 - 42xy
= 400 - 42*4
= 400 - 168
= 232
So, the answer is (b) 232.
2.
So, (a) 100.
3.
So, the answer is (c) 7.
4. (d) is the answer.
CHECK :-
5. Given,
ab = 8
a + b = 6
To find:
a² + b²
Solution:
So, the answer is (c) 20.
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