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secondary 2 | Maths
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Date Posted: 5 years ago
Views: 205
The sisters have ages x and 28 - x
Since sum of the squares of their ages Is 400,
x2 + (28 - x)2 = 400
x2 + 784 - 28x - 28x + x2 = 400
2x2 - 56x + 384 = 0
x2 - 28x + 192 = 0
(x - 16) (x - 12) = 0
x = 16 or x = 12
Then 28 - x = 12 or 16
So the sisters have ages 12 and 16
The younger one has age 12
Since sum of the squares of their ages Is 400,
x2 + (28 - x)2 = 400
x2 + 784 - 28x - 28x + x2 = 400
2x2 - 56x + 384 = 0
x2 - 28x + 192 = 0
(x - 16) (x - 12) = 0
x = 16 or x = 12
Then 28 - x = 12 or 16
So the sisters have ages 12 and 16
The younger one has age 12
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done
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“The sum of the squares of...” is not the same as “the square of the sum of...”.
Date Posted:
5 years ago
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