Question

Solve the following pair of equations by substitution method 3x+y=-3,x+y=3

Answer 1

Answer:

Step-by-step explanation:

3x+y= -3

so y= -3-3x

put the value of y in x+y=3

  x+(-3-3x)=3

  -2x-3=3

 -2x=6

  or x= -3

put value of x in y= -3-3x to get y

y=-3-3(-3)

  = -3+9

 =6

Answer 2

$\bf{\underline{\underline{Given}}}$

$\mathsf{\bigstar\: \: 3x + y = -3}$

$\mathsf{\bigstar\: \: x + y = 3}$

$\bf{\underline{\underline{To\: find}}}$

$\mathsf{\bigstar\: \: Value\: of \: x \: and \: y}$

$\bf{\underline{\underline{Solution}}}$

$\mathsf{\implies\: 3x + y = -3 \: \: \rightarrow \: (1)}$

$\mathsf{\implies\: x + y = 3 \: \: \rightarrow \: (2)}$

By substitution method:

$\mathsf{\implies \: y = 3 - x \: \: \red{[Using\: (2)]}}$

From eqn (1)

$\mathsf{\implies \: 3x + y = -3}$

$\mathsf{\implies \: 3x + 3 - x = -3}$

$\mathsf{\implies \: 2x = -6}$

$\mathsf{\implies \: \green{x = -3}}$

so, $\mathsf{\implies\: y = 3 - (-3) \: \red{[Putting\:x = -3]}}$

$\mathsf{\implies \: \green{y = 6} }$