slope intercept form equation *

[tamiatha]

write an equation in slope-intercept form for the line that has a slope of 3 and passes through (-1,2).
my solution:
y = mx +b
m = slope = 3
x = -1
b = y intercept = 2

y = 3 (-1) + 2

y = -3 + 2

i thought i had this one right however it is not one of my answer choices
what have i done wrong
thank you for your continued help

 

[Aladdin]

Re: slope intercept form equation

y-y1=a(x-x1)

which gives


y=3x+5

 

[Mrspi]

Re: slope intercept form equation

write an equation in slope-intercept form for the line that has a slope of 3 and passes through (-1,2).
my solution:
y = mx +b
m = slope = 3
x = -1
b = y intercept = 2

y = 3 (-1) + 2

y = -3 + 2

i thought i had this one right however it is not one of my answer choices
what have i done wrong
thank you for your continued help

Substitute 3 (the slope) for "m" in the equation:
y = mx + b
y = 3x + b

Now, you know that the point (-1, 2) is on the line. Note that this point is NOT on the y-axis, so it does NOT represent the y-intercept, b. But, you DO know that when x = -1, y = 2. Substitute -1 for x and 2 for y:

y = 3x + b
2 = 3(-1) + b

And solve that for b.