Find the equation of the line that contains the point (-1, 2) and is perpendicular to the line 2x + 4y = -2

Question

anonymous · Answer

slope of the required st. line = -1/(-1/2) = 2
y-2=2(x-(-1))
y-2=2x+2
y=2x+4

radar · Answer

Do you know the relationship between a line and it perpendicular with regard to slope?

anonymous · Answer

no

radar · Answer

There slope will be negative reciprocal.  As shown by CoCoTsoi the slope of the line 2x+4y=-2
4y=-2x-2
y=(-2/4)-1/2    The coefficient of x is the slope is -2/4 or -1/2 so the negative reciprocal is 2  This is shown in the first line of the solution in the first post above.

anonymous · Answer

ok thank you

radar · Answer

It is an important relationship.  The reciprocal of a number is a 1 divided by that number like the reciprocal of 3 is 1/3   of course a negative reciprocal of 3 is -1/3    the negative reciprocal of -3/5 would be 5/3 etc.