Respuesta :
QUESTION 1
The given system of equation is
[tex]y=x-6...eqn1[/tex]
and
[tex]3x+2y=8...eqn2[/tex]
Let us substitute equation (1) into equation (2) to get,
[tex]3x+2(x-6)=8[/tex]
We expand the bracket to get,
[tex]3x+2x-12=8[/tex]
We simplify to get.
[tex]5x-12=8[/tex]
We group like terms to get
[tex]5x=8+12[/tex]
[tex]\Rightarrow 5x=20[/tex]
[tex]\Rightarrow x=4[/tex]
We now substitute [tex]x=4[/tex] in to equation (1) to obtain,
[tex]y=4-6=-2[/tex]
The correct answer is option A.
QUESTION 2
The given system of equations is
[tex]y-x=9...eqn1[/tex]
and
[tex]10+2x=-2y...eqn2[/tex]
We make y the subject in equation (2) to get,
[tex]y=-x-5..eqn3[/tex]
We put equation (3) into equation (1) to obtain,
[tex]-x-5-x=9[/tex]
We group like terms to get,
[tex]-x-x=9+5[/tex]
This implies that,
[tex]-2x=14[/tex]
We divide through by [tex]-2[/tex] to get,
[tex]x=-7[/tex]
Hence the x-coordinate is [tex]-7[/tex]
QUESTION 3
The given system is
[tex]y=3x-1..eqn1[/tex]
and
[tex]x-y=-9...eqn2[/tex]
We make [tex]x[/tex] the subject in equation (2) to get,
[tex]x=y-9...eqn3[/tex]
We put equation (3) into equation (1) to obtain,
[tex]y=3(y-9)-1[/tex]
We expand the bracket to get,
[tex]y=3y-27-1[/tex]
Group like terms to get,
[tex]y-3y=-27-1[/tex]
We simplify to get;
[tex]-2y=-28[/tex]
This implies that,
[tex]y=14[/tex]
Therefore the y-coordinate is 14.