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Question -

Do the following pair of linear equations have no solution? Justify youranswer.



Answer -

(i) 2+ 4=3

12+ 6=6

(ii) x =2y

= 2x

(iii) 3–3 = 0

2+ 2/3=2


Solution:

The Condition for nosolution = a1/a= b1/b2 ≠c1/c2 (parallel lines)

(i) Yes.

Given pair ofequations are,

2x+4y – 3 = 0 and 6x +12y – 6 = 0

Comparing theequations with ax+ by +c = 0;

We get,

a1 =2, b1 = 4, c1 = – 3;

a2 =6, b2 = 12, c2 = – 6;

a1 /a2 =2/6 = 1/3

b1 /b2 =4/12 = 1/3

c1 /c2 =– 3/ – 6 = ½

Here, a1/a2 =b1/b≠ c1/c2, i.eparallel lines

Hence, the given pairof linear equations has no solution.

(ii) No.

Given pair ofequations,

x = 2y or x – 2y = 0

y = 2x or 2x – y = 0;

Comparing theequations with ax+ by +c = 0;

We get,

a1 =1, b1 = – 2, c1 = 0;

a2 =2, b2 = – 1, c2 = 0;

a1 /a2 =½

b1 /b2 =-2/-1 = 2

Here, a1/a2 ≠ b1/b2.

Hence, the given pairof linear equations has unique solution.

(iii) No.

Given pair ofequations,

3x + y – 3 = 0

2x + 2/3 y = 2

Comparing theequations with ax+ by +c = 0;

We get,

a1 =3, b1 = 1, c1 = – 3;

a2 =2, b2 = 2/3, c2 = – 2;

a1 /a2 =2/6 = 3/2

b1 /b2 =4/12 = 3/2

c1 /c2 =– 3/-2 = 3/2

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

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