Find the equation of the line that passes through the point of intersection of x + 2y = 9 and 4x -2y = -4 and the point of intersection of intersection of the lines 3x - 4y = 14 and 3x + 7y = -8.

Find the equation of the line that passes through the point of intersection of x 2y 9 and 4x 2y 4 and the point of intersection of intersection of the lines 3x class=

Respuesta :

Answer:

[tex]y=-6x+10[/tex]

Step-by-step explanation:

The point of intersection of

[tex]x+2y=9...eqn1[/tex]


and


[tex]4x-2y=-4...eqn2[/tex]

is the solution of the two equations.


We add equation (1) and equation(2) to get,

[tex]x+4x+2y-2y=9+-4[/tex]


[tex]\Rightarrow 5x=5[/tex]


[tex]\Rightarrow x=1[/tex]

We put [tex]x=1[/tex] into equation (1) to get,

[tex]1+2y=9[/tex]

[tex]\Rightarrow 2y=9-1[/tex]

[tex]\Rightarrow 2y=8[/tex]

[tex]\Rightarrow y=4[/tex]


Therefore the line passes through the point, [tex](1,4)[/tex].


The line also passes through the point of intersection of

[tex]3x-4y=14...eqn(3)[/tex]

and

[tex]3x+7y=-8...eqn(4)[/tex]

We subtract equation (3) from equation (4) to obtain,

[tex]3x-3x+7y--4y=-8-14[/tex]


[tex]\Rightarrow 11y=-22[/tex]

[tex]\Rightarrow y=-2[/tex]


We substitute this value into equation (4) to get,

[tex]3x+7(-2)=-8[/tex]


[tex]3x-14=-8[/tex]


[tex]3x=-8+14[/tex]


[tex]3x=6[/tex]

[tex]x=2[/tex]

The line also passes through

[tex](2,-2)[/tex]



The slope of the line is

[tex]slope=\frac{4--2}{1-2} =\frac{6}{-1}=-6[/tex]


The equation of the line is

[tex]y+2=-6(x-2)[/tex]

[tex]y+2=-6x+12[/tex]


[tex]y=-6x+10[/tex] is the required equation