Question

Graphically, the pair of equations 7x-y = 5; 21x=3y =10
represent two lines which are
a) intersecting at one point (b) Parallel
(c) Coincident (d) none of above.​

Answer 1

b. parallel lines is correct

Answer 2

(b) Parallel

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

Tips:

The two lines

ax + by + c = 0 and dx + ey + f = 0 are parallel lines, when

$\dfrac{a}{d}=\dfrac{b}{e}$

In another way, we can say that the parallel condition holds only when the constant part is unequal for the equations: ax + by = c and ax + by = k.

Step-by-step explanation:

The given lines are

7x - y = 5 ... ... (1)

21x - 3y = 10

⇒ 7x - y = $\dfrac{10}{3}$ ... ... (2)

Since only the constant part of (1) and (2) are different, they represent parallel lines.

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