Question

For two simultaeous linear equations with two variables, say $x$ and $y,$ arrange the given steps in proper order to find solution of the equations using substitution.

Step a: Solve the $2^{nd}$ equation to find $y.$

Step b: Substitute the value of $y$ in one of the given equations to obtain the value of $x.$

Step c: Inject/ substitute $x$ in the $2^{nd}$ equation to make it a linear equation in one variable.

Step d: In $1^{st}$ equation, solve for $x$ in terms of $y.$

• A. $a\to b\to c\to d$
• B. $d\to c\to a\to b$

Answer 1

The correct option is B $d\to c\to a\to b$

Two linear equations with two variables, $x$ and $y,$ we proceed as per the following steps.

Step 1: Solve for $x$ in terms of $y.$

Step 2: Inject/ substitute this $x$ in the $2^{nd}$ equation to make it a linear equation in one variable.

Step 3: Solve the $2^{nd}$ equation to find $y.$

Step 4: Substitute the value of $y$ in one of the given equations to obtain the value of $x.$

For example, let's solve the below two equations.
$x+y=4$
$x-y=2$

From the $1^{st}$ equation, $x=4-y$
Substituting this in the $2^{nd}$ equation we get,
$4-y-y=2$
$\Rightarrow -2y=2-4$
$\Rightarrow -2y=-2$
$\Rightarrow y=1$

Substituting this in the $1^{st}$ equation we get,
$x=4-1=3$
$\therefore (3,1)$ is the solution of the linear equations.