posted by trixie on .
it says write the equation of the vertical line that passes through the point (7,-3). what do i need to start it off?
find the equation for the line with undefined slope and passing through the point (-1,-2). what do i need to start that off?
what equation do i use to find the slope-intercept?
whats the point-slope form?
any vertical line has an undefined slope and always has the form x = c, where c is a constant.
All you need is a point, then simply state it as x = 'the x of the given point'
so for your first one : x = 7
for the second x = -1
slope-intercept form looks like this
y = mx + b, where m is the slope and b is the y-intercept
e.g. y = 4x + 9
the slope is 4 and the y-intercept is 9
the point-slope form is one of the best ways to find the equation of a straight line, given the slope and a point
e.g. given the point (5,-3) and slope of 2/3, find the equation
y - (-3) = (2/3)(x - 5)
3(y+3) = 2(x-5)
3y + 3 = 2x - 10
you can now re-arrange it to end up with any version they ask for.
my last line should have been
3y + 9 = 2x - 10