Quantitative Aptitude Ques 1541

Question: For what value of k, the following equations have no solution? $ 9x+4y=9,;7x+ky=5 $

Options:

A) 3

B) 4.7

C) 28/9

D) 9/28

Show Answer

Answer:

Correct Answer: C

Solution:

  • (c) Given equations, $ 9x+4y=9 $ and $ 7x+ky=5 $ Standard equations $ a _1x+b _1y=c _1 $ and $ a _2x+b _2y=c _2 $
    We know that, equations to have no solution the condition is $ \frac{a _1}{a _2}=\frac{b _1}{b _2} $ Now, comparing given equations with standard equations, we get $ \frac{9}{7}=\frac{4}{x} $
    $ \Rightarrow $ $ k=\frac{4\times 7}{9}=\frac{28}{9} $ Hence, $ k=\frac{28}{9} $ for the equations to have no solution.