Write the equation of the line which passes through (1, –1) and is perpendicular to the line with equation 4y–x=1

Question

ranga · Answer

4y–x=1
4y = x + 1
y = 1/4x + 1/4
slope of the line = 1/4

slope of perpendicular line is the negative reciprocal of this slope.
m = -4
Equation of a line in slope-intercept form is: y = mx + b
y = -4x + b
It passes therough the point (1,-1)
put x = 1 and y = -1  in y = -4x + b and solve for b.

anonymous · Answer

I figured out the slope (m) is $$\frac{ 1 }{ 4 }$$

anonymous · Answer

Ok... so, y+1=-4(x-1)

anonymous · Answer

I got 4x+y=3

ranga · Answer

Yes.  y+1=-4(x-1) is the point-slope form of the line and is correct.
They don't tell you which form they want.
You can also write the equation in the slope-intercept form in which case you can solve for b as I mentioned above.  
You can also write the equation in standard form and 4x+y=3 is correct.

anonymous · Answer

Great! I think they want standard form. Thanks a lot ranga!

ranga · Answer

You are welcome.