algebra

posted by on .

could someone check my answers to these few questions?

"What is the equation of the line, in slope-intercept 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?

• algebra - ,

y = mx + b

-8 = (3)(-1) + b
-8 = -3 + b
-8 + 3 = -3 + 3 + b

b = -5
y = 3x -5

• algebra - ,

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)

• algebra - ,

this is slope intercept form: y - y1 = m(x-x1)

• algebra - ,

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

• algebra - ,

(-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

• algebra - ,

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.

• algebra - ,

oops, sorry!