Question

Q.5. Find the value of k if the following equations are consistent
7x - ky = 4
2x + 5y = 9 and 2x + y = 8​

Answer 1

Answer:

$a1 = 7 \: b1 = -k \: c1 = 4 \\ a2 = 2 \: b2 = 5 \: c2 = 9 \\ \frac{7}{2} = \frac{-k}{5} = \frac{4}{9} \\ \frac{-k}{5} = \frac{7}{2} \\ -k = \frac{7 \times 5}{2} \\ -k = \frac{35}{2} \\ hence \: k = \frac{-35}{2}$