# [SOLVED] stumped on college algebra problem: equation of a line

• Feb 9th 2009, 12:09 PM
mathnotwiz
[SOLVED] stumped on college algebra problem: equation of a line
Here is the problem: http://img22.imageshack.us/my.php?image=...

an answer is required for each box that you see, so could you please state what is supposed to go in each box.

i've been working on this problem for 2 hours but can't figure it out. i would be very grateful for some help.
• Feb 9th 2009, 12:39 PM
Quote:

Originally Posted by mathnotwiz
Here is the problem: http://img22.imageshack.us/my.php?image=...

an answer is required for each box that you see, so could you please state what is supposed to go in each box.

i've been working on this problem for 2 hours but can't figure it out. i would be very grateful for some help.

y-2=-2(x-9)
y=-2(x-9)+2
=-2x+18+2=-2x+20
So -2 goes in the first box, 20 goes in the second box
The other two boxes are left blank. Notice the OR, it means you don't have to fill it up if it don't apply.
• Feb 9th 2009, 12:48 PM
Air
Quote:

Originally Posted by mathnotwiz
Here is the problem: http://img22.imageshack.us/my.php?image=...

an answer is required for each box that you see, so could you please state what is supposed to go in each box.

i've been working on this problem for 2 hours but can't figure it out. i would be very grateful for some help.

An equation for the linear line is $\displaystyle y=mx+c$ where $\displaystyle y,x$ are the variables, $\displaystyle m$ is the gradient (slope) and $\displaystyle c$ is the $\displaystyle y$-intercept (where it crosses $\displaystyle y$-axis).

You are given the information: $\displaystyle m= -2$ and the co-ordinate $\displaystyle (x,y) = (9,2)$. Putting this information into the equation and working out the value of $\displaystyle c$ will get you your equation (and the gaps to be filled).

$\displaystyle y=mx+c$
$\displaystyle \therefore 2 = -2(9) + c \rightarrow c = 20$
$\displaystyle \therefore y = -2x+20$