Question

Find the value of x and y using cross multiplication method:
$x-6y=2$ and $x+y=4$

• A. $(\frac{26}{7},\frac{2}{7})$
• B. $(\frac{-26}{7},\frac{2}{7})$
• C. $(\frac{26}{7},\frac{-2}{7})$
• D. $(\frac{-26}{7},\frac{-2}{7})$

Answer 1

The correct option is A $(\frac{26}{7},\frac{2}{7})$

$x-6y=2$ ----- (1)

$x+y=4$ ----- (2)

First use formula for cross multiplication method:

$\frac{x}{b_1{c}_2-b_2{c}_1}=\frac{y}{c_1{a}_2-a_1{c}_2}=\frac{-1}{a_2{b}_2-a_2{b}_1}$

So, from equation (1) and (2) we can write the value of a, b and c.

$\frac{x}{(-6)\times 4-1\times 2}=\frac{y}{2\times 1-1\times 4}=\frac{-1}{1\times 1-1\times (-6)}$

$\frac{x}{-24-2}=\frac{y}{2-4}=\frac{-1}{1+6}$

$\frac{x}{-26}=\frac{y}{-2}=\frac{-1}{7}$

$\frac{x}{-26}=\frac{-1}{7}$

$x=\frac{26}{7}$

$\frac{y}{-2}=\frac{-1}{7}$

$y=\frac{2}{7}$

The solution is $(\frac{26}{7},\frac{2}{7})$