Question

SOLVE FOR X AND Y USING ELIMINATION METHOD
2(ax-by) + (a+4b) =0
2(bx+ay) + b-4a =0​

Answer 1

Step-by-step explanation:

It's a system of 2 linear equations in variables x & y & constant terms a & b which need to be solved simultaneously. According to my knowledge, one can't solve simultaneous equations by cross multiplication. I solve it by equating coefficients.

You can write these equations like :

2ax - 2by = -a-4b ..... (1)

2bx + 2ay = 4a-b .........(2)

Now, multiplying (1) by a & (2) by b,

2a^2x - 2aby = -a^2 - 4ab ......(3)

2b^2x + 2aby = -b^2 + 4ab .....(4)

Adding (3) & (4),

2 (a^2+b^2) x = -(a^2+b^2).

Obviously, x = -1/2.

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