Question

please answer this question no 13

Answer 1

Given Equation is 3x - 4y = 10 ----- (1)

Given Equation is xy = -1 ---- (2)

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On squaring (1) on both sides, we get

= > (3x - 4y)^2 = (10)^2

We know that (a - b)^2 = a^2 + b^2 - 2ab.

= > 9x^2 + 16y^2 - 24xy = 100

= > 9x^2 + 16y^2 - 24(-1) = 100

= > 9x^2 + 16y^2 + 24 = 100

= > 9x^2 + 16y^2 = 100 - 24

= > 9x^2 + 16y^2 = 76.

Hope this helps!

Answer 2

(a-b)^2= a^2 - 2ab +b^2

(3x-4y)^2=(3x)^2 - 2×3x×4y + (4y)^2

(10)^2= 9x^2-24 xy + 16y^2

100= 9x ^2 + 24 + 16y^2

9x ^2 + 16y ^2= 100 - 24
9x^2 + 16y ^2 = 76