# math/algebra1a

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**Confused**
.

write the equation of the line which has y-intercept (0,5) and is perpendicular to the line with equation y=-3x +1

a) y=-3x + 5

b) y= 1/3x + 5

c) y= 3x + 5

d) y= -1/3x + 5

The slope of the 2nd equation is -3...because the equation of a line is y=mx+b, where "m" is the slope and b is the y-intercept. So since the slope of the given equation is -3. To get the slope of the line perpendicular to that, you would get the negative reciprocal of -3.

-3 is -3/1. You would flip it to 1/-3 and multiply by -1 to get 1/3 to get your perpendicular slope. And since the y-intercept is (0,5), you only need the y-value, which is 5.

So your equation would be y=1/3x + 5.