Question

The number of integral values of m, for which the x-co-ordinate of the point of intersection of the lines 3x + 4y = 9 and y = mx + 1 is also an integer is

• A. 2
• B. 4
• C. 1

Answer 1

The correct option is A 2

Solving 3x + 4y = 9, y = mx we get $x=\frac{5}{3+4m}$
x is an integer if 3 + 4m = 1, - 1, 5, - 5
$\therefore m=\frac{-2}{4},\frac{-4}{4},\frac{2}{4},\frac{-8}{4}$. So, m has two integral values.