7y + 4x = 3; (-4, -7) Write the equation in slope intercept form of the line that is perpendicular to the graph of the equation and passes through the given point.

Respuesta :

Solving the given equation for y results in  y = (-4/7) x + (a constant).

The new line has a slope that is the negative reciprocal of -4/7.  That slope is +7/4.

The new line passes thru (-4, -7).  Thus,

the equation for this new line is  y - (-7) = (7/4)(x - [-7]), or 

y + 7 = (7/4)(x+7)

Let's put this into slope-intercept form:

y = -7 + (7/4)x + (49/4), or        y = (7/4)x + (49/4) - 7,   or

y = (7/4)x + 21/4   (answer in slope-intercept form)

Answer:

[tex]y=\frac{7}{4} x[/tex]

Step-by-step explanation:

we have the original line equation

[tex]7y + 4x = 3[/tex]

clearing for y:

[tex]7y=-4x+3\\y=\frac{-4}{7}x+ \frac{3}{7}[/tex]

Now we have an equation of the form slope- intercept:

[tex]y=mx+b[/tex]

where m is the slope and b is the y-intercept.

thus, the slope of the original line is:

[tex]m=\frac{-4}{7}[/tex]

Now to find the new line, since it has to be perpendicular their slopes must satisfy the following:

[tex]m*m_{1}=-1[/tex]

where m is the slope of the original line, and m1 is the slope of the new line:

[tex]\frac{-4}{7}*m_{1}=-1\\ m_{1}=\frac{-1*7}{-4}\\ m_{1}=\frac{7}{4}[/tex]

this is the slope of the new perpendicular line that passes trough the point (-4,-7), so now we use the point slope equation to find the equation of said line:

[tex]y-y_{1}=m_{1}(x-x_{1})[/tex]

where we know [tex]m_{1}=\frac{7}{4}[/tex], and from the point (-4,-7) [tex]x_{1}=-4, y_{1}=-7[/tex]

so we have:

[tex]y-(-7)=\frac{7}{4} (x-(-4))\\y+7=\frac{7}{4} (x+4)[/tex]

and we clear for y to leave the equation in the slope intercept form:

[tex]y=\frac{7}{4} (x+4)-7\\y=\frac{7}{4} x+\frac{7}{4}*4 -7\\\\y=\frac{7}{4} x+7-7\\y=\frac{7}{4} x[/tex]