Question

Graphically , the pair of equation 7x - y = 5 ; 21x - 3y = 10 , represents two lines which are :​

Answer 1

Graphically, the pair of equations 7x - y = 5 and 21x - 3y = 10 represent two lines which are parallel lines.

Explanation:

• The first equation is 7x - y = 5
• The second equation is 21x - 3y = 10

• Multiplying 3 to the first equation, we get
• 21x - 3y = 15, whose left hand side is similar to the that of the second equation.

• The constant part for the equations are different.

• Thus the lines are parallel to each other.

Answer 2

$Given \: pair \: of \: equations :$

$7x-y=5 \: --(1)$

$If \: x = 0 \:then \: y = -5$

$If \:x = 1 \: then \: y = 2$

plotting the points A(0,-5) and B(1,2) on the graph and joining them we get a straight line.

$21x - 3y = 10 \:--(2)$

$If \: x = \frac{1}{3} \:then \: y = -1$

$If \: x = \frac{1}{21} \:then \: y = -3$

plotting the points C and D on the graph and joining them we get a straight line.

From the graph ,we conclude that these two lines are parallel.

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