Question

Solve the following pair of simultaneous equations
$0.2x+0.3y-0.11=0$, $0.7x-0.5y+0.08=0$

• A. $x=0.9$ and $y=-0.2$
• B. $x=1$ and $y=-1.6$
• C. $x=0.1$ and $y=0.3$
• D. $x=-2$ and $y=-0.7$

Answer 1

Answer: (C)

$x=0.1$ and $y=0.3$


The given equations are:
$0.2x+0.3y-0.11=0$ ....(1)
$0.7x-0.5y+0.08$ $=$ $0$ ....(2)
Multiply equation (1) by $5$ and equation (2) by $3$,
$x+1.5y-0.55$ $=$ $0$
$2.1x-1.5y+0.24$ $=$ $0$
Adding (1) and (2), we get
$3.1x-0.31$ $=$ $0$
$x$ $=$ $\frac{0.31}{3.1}=0.1$
Substitute $x$ $=$ $0.1$ in equation (1), we have
$0.02+0.3y-0.11$ $=$ $0$
$0.03y$ $=$ $0.09$
$0.3y$ $=$ $0.09$
$y$ $=$ $0.3$
Hence, $x$ $=$ $0.1$ and $y$ $=$ $0.3$