Answer :

1) Given y = x+2 and y = -4x-8.

Since the left hand sides of both equations are same, equate the right hand side of both the equations.

[tex]x+2=-4x-8[/tex]

Add 4x on both sides.

[tex]\begin{gathered} x+2+4x=-4x-8+4x \\ 5x+2=-8 \end{gathered}[/tex]

Add -2 on both sides.

[tex]\begin{gathered} 5x+2-2=-8-2 \\ 5x=-10 \end{gathered}[/tex]

Divide by 5 on both sides.

[tex]\begin{gathered} x=-\frac{10}{5} \\ =-2 \end{gathered}[/tex]

Substitute the value of x into y = x+2.

[tex]\begin{gathered} y=-2+2 \\ =0 \end{gathered}[/tex]

Solution is (-2,0).

2) Given y = 3x+1 and y = -2x+6.

Since the left hand sides of both equations are same, equate the right hand side of both the equations.

[tex]3x+1=-2x+6[/tex]

Add 2x on both sides.

[tex]\begin{gathered} 3x+1+2x=-2x+6+2x \\ 5x+1=6 \end{gathered}[/tex]

Add -1 on both sides.

[tex]\begin{gathered} 5x+1-1=6-1 \\ 5x=5 \end{gathered}[/tex]

Divide by 5 on both sides.

[tex]\begin{gathered} x=\frac{5}{5} \\ =1 \end{gathered}[/tex]

Substitute the value of x into y = 3x+1.

[tex]\begin{gathered} y=3\cdot1+1 \\ =4 \end{gathered}[/tex]

Solution is (1, 4).

3) Given y = -3x-6 and 6x+2y = -2.

Substitute -3x-6 for y into 6x+2y = -2.

[tex]\begin{gathered} 6x+2(-3x-6)=-2 \\ 6x-6x-12=-2 \\ -12=-2 \end{gathered}[/tex]

which is not possible. Hence the given system of equations has no solution.

4) Given y = -5 and -8x+4=-20.

From the second equation, -8x+4 = -20, solve for x.

Add -4 on both sides.

[tex]\begin{gathered} -8x+4-4=-20-4 \\ -8x=-24 \end{gathered}[/tex]

Divide by -8 on both sides.

[tex]\begin{gathered} x=\frac{-24}{-8} \\ =3 \end{gathered}[/tex]

Solution is (-5, 3).

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