# Thread: the equation of a straight line is 3x+2y=11. find the equation of a parrallel line pa

1. ## the equation of a straight line is 3x+2y=11. find the equation of a parrallel line pa

i made it y=-3/2 x +11.5

but i think its wrong help

2. Originally Posted by coyoteflare
i made it y=-3/2 x +11.5

but i think its wrong help
$\displaystyle 3x+2y=11$

Transpose (move) the 3x to the right side of the equation, thus changing its sign.

$\displaystyle 2y=-3x+11$

Divide each term by 2

$\displaystyle y=-\frac{3}{2}x+\frac{11}{2}$

3. Originally Posted by masters
$\displaystyle 3x+2y=11$

Transpose (move) the 3x to the right side of the equation, thus changing its sign.

$\displaystyle 2y=-3x+11$

Divide each term by 2

$\displaystyle y=-\frac{3}{2}x+\frac{11}{2}$
but surely you have to substitute 5,4 in somewhere?

4. Originally Posted by coyoteflare
but surely you have to substitute 5,4 in somewhere?
I'm sorry. I'm not seeing the rest of your question.....

Are you trying to find the equation of a line through (5,4) that is parallel to $\displaystyle y=-\frac{3}{2}x+\frac{11}{2}$?

5. yeh thats what im after [:

6. If that be the case, then we will use the same slope as:

$\displaystyle y=-\frac{3}{2}x+\frac{11}{2}$ which is $\displaystyle -\frac{3}{2}$

We need to find the y-intercept. Use the slope-intercept form of the linear equation and use the point given (5, 4).

$\displaystyle y=mx+b$

$\displaystyle 4=-\frac{3}{2}(5)+b$

$\displaystyle 4=-\frac{15}{2}+b$

$\displaystyle \frac{23}{2}=b$

Substituting back into y=mx+b, we have

$\displaystyle y=-\frac{3}{2}x+\frac{23}{2}$