Question

Solve the following pairs of linear (simultaneous) equation by the method of elimination:$1.5x+0.1y=6.2$, $3x-0.4y=11.2$

• A. $x=-2,y=6$
• B. $x=4,y=2$
• C. $x=-5,y=-7$
• D. $x=1,y=6$

Answer 1

The correct option is B $x=4,y=2$

Multiply the equation $1.5x+0.1y=6.2$ by $20$. Then we get the following equations:

$3x-0.4y=\mathrm{11.2.........}\left(1\right)$

$3x+0.2y=\mathrm{12.4.........}\left(2\right)$

Subtract Equation (2) from Equation (1) to eliminate $x$, because the coefficients of $x$ are the same. So, we get

$(3x-3x)+(-0.4y-0.2y)=11.2-12.4$

i.e. $-0.6y=-1.2$

i.e. $y=2$

Substituting this value of $y$ in the equation $3x-0.4y=11.2$, we get

$3x-0.8=11.2$

i.e. $3x=12$

i.e. $x=4$

Hence, the solution of the equations is $x=4,y=2$.