Question

Find the value of k so that the pair of equation x + 2y = 5 and 3 x + k y + 15 = 0 have a unique solution

Answer 1

Answer:

$k = 6 \: and \: - 6$

Step-by-step explanation:

x + 2y = 5 (1)

3x + ky +15 =0

3x + ky = -15 (2)

$\frac{a1}{a2} = \frac{b1}{b2} = \frac{c1}{c2}$

$\frac{1}{3} = \frac{2}{k} = \frac{5}{ - 15}$

$\frac{a1}{a2} = \frac{b1}{b2}$

$\frac{1}{3} = \frac{2}{k}$

k = 6

$\frac{b1}{b2} = \frac{c1}{c2}$

$\frac{2}{k} = \frac{5}{ - 15}$

5k = -30

$k = \frac{ - 30}{5} = - 6$

k = -6