Question

Solve each of the following systems of equations by using the method of cross multiplication:

$3x+2y+25=0$,

$2x+y+10=0.$

Answer 1

$3x+2y+25=0$ ………….(i)

$2x+y+10=0$…………….. (ii)

Here $a_1=3,b_1=2,c_1=25$

$a_2=2,b_2=1,c_2=10$

By cross multiplication method,

$\frac{x}{20-25}=\frac{-y}{30-50}=\frac{1}{3-4}$

$\frac{x}{-5}=\frac{-y}{-20}=\frac{1}{-1}$

Now,

$\frac{x}{-5}=\frac{1}{-1}$

$=x=5$

And,

$\frac{-y}{-20}=\frac{1}{-1}$

$y=-20$

The solution of the given system of equation is 5 and -20 respectively.