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secondary 2 | Maths
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Date Posted: 3 years ago
Views: 342
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(3x - 3y)^2 = 9x^2 - 18xy + 9y^2
= 9(x^2 + y^2) - 18(xy)
Sub in x^2 + y^2 = 20 and XY = 7,
(3x - 3y)^2 = 9(20) - 18(7) = 54
= 9(x^2 + y^2) - 18(xy)
Sub in x^2 + y^2 = 20 and XY = 7,
(3x - 3y)^2 = 9(20) - 18(7) = 54
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