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Question -

Do the following pairof linear equations have no solution? Justify your answer.



Answer -

(i) 2x┬а+ 4y┬а=3

12y┬а+ 6x┬а=6

(ii)┬аx┬а=2y

y┬а= 2x

(iii) 3x┬а+┬аy┬атАУ3 = 0

2x┬а+ 2/3y┬а=2

Solution:

The Condition for nosolution =┬аa1/a2┬а= b1/b2┬атЙаc1/c2┬а(parallel lines)

(i) Yes.

Given pair ofequations are,

2x+4y тАУ 3 = 0 and 6x +12y тАУ 6 = 0

Comparing theequations with ax+ by +c = 0;

We get,

a1┬а=2, b1┬а= 4, c1┬а= тАУ 3;

a2┬а=6, b2┬а= 12, c2┬а= тАУ 6;

a1┬а/a2┬а=2/6 = 1/3

b1┬а/b2┬а=4/12 = 1/3

c1┬а/c2┬а=тАУ 3/ тАУ 6 = ┬╜

Here, a1/a2┬а=b1/b2┬атЙа┬аc1/c2, i.eparallel lines

Hence, the given pairof linear equations has no solution.

(ii) No.

Given pair ofequations,

x = 2y or x тАУ 2y = 0

y = 2x or 2x тАУ y = 0;

Comparing theequations with ax+ by +c = 0;

We get,

a1┬а=1, b1┬а= тАУ 2, c1┬а= 0;

a2┬а=2, b2┬а= тАУ 1, c2┬а= 0;

a1┬а/a2┬а=┬╜

b1┬а/b2┬а=-2/-1 = 2

Here, a1/a2┬атЙа┬аb1/b2.

Hence, the given pairof linear equations has unique solution.

(iii) No.

Given pair ofequations,

3x + y тАУ 3 = 0

2x + 2/3 y = 2

Comparing theequations with ax+ by +c = 0;

We get,

a1┬а=3, b1┬а= 1, c1┬а= тАУ 3;

a2┬а=2, b2┬а= 2/3, c2┬а= тАУ 2;

a1┬а/a2┬а=2/6 = 3/2

b1┬а/b2┬а=4/12 = 3/2

c1┬а/c2┬а=тАУ 3/-2 = 3/2

Here, a1/a2┬а=b1/b2┬а= c1/c2, i.e coincidentlines

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