algebra
posted by caduceus on .
could someone check my answers to these few questions?
"What is the equation of the line, in slopeintercept form, that goes through the point (1, 8) with m = 3 ?"
here's my work:
y + 8 = 3(x + 1) [i put the values into the equation.]
y = 3x + 5 [i multiplied 3 by 1 and added 8 to both sides.]
is this right? my main question is whether or not i would add or subtract 8 in this situation. i know that y  (8) is exactly the same as y + 8, so, in that case, would i subtract 8 from both sides?

y = mx + b
8 = (3)(1) + b
8 = 3 + b
8 + 3 = 3 + 3 + b
b = 5
y = 3x 5 
unfortunately, y = 3x 5 is not an answer. here are my option:
A. y = 3x + 11
B. y = 3x + 5
C. y = 3x  11
D. y + 1 = 3(x + 8) 
this is slope intercept form: y  y1 = m(xx1)

oh wait nevermind, oops, that is not slope intercept form

(1, 8)
m = 3
y y1 = m (x x1)
y (8) = 3 ( x  (1))
y + 8 = 3(x + 1)
y + 8 = 3x + 3
y + 8  8 = 3x + 3 8
y = 3x 5
Slope intercept form
y = mx + b 
The problem is the slope.
All the options indicate a slope of 3, but you stated the slope to be +3
Kuai's solution is correct according to the data supplied. 
oops, sorry!