Question

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If 3x + 4y = 13 and xy = 1, find 3x – 4y.​

Answer 1

Answer:

xy=1

x=1/y

3x+4y=13

3/y+4y=13

3+4y^2=13y

4y^2-13y+3=0

4y^2-12y-y+3=0

4y(y-3)-1(y-3)=0

y=3 | y=1/4

x=1/y

x=1/3

3x-4y

=3×1/3-4×3

=1-12

=-11

Answer 2

Answer:

Here's your answer!

Hope it helps!