Algebra and Applications Test 2

Question : 39 of 40

Marks: +1, -0

3x + 2y = 12 and xy = 6, then the value of

3x ^ 2 + 4y ^ 2

is:

Solution:

3x + 2y = 12 ......(i)
xy = 16
Squaring both the sides of equation (i) we get

(3x + 2y)^ 2 = (12)^2

9x^ 2 + 4y^ 2 + 12xy = 144

9x^ 2 + 4y^ 2 + 12(6) = 144

9x^2 + 4y^2 = 144 - 72

9x^2 + 4y^2 = 72

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