Help with Algebra homework?

Hi fwog_fwo

I think the main point for you here is: when you are dealing with lines, parallel means: same slope. slope is m in the standard form of a line: y=mx+b (if you have m and b, you can construct a line)

the given line 9x=8y+3 doesn´t have this form yet, to change that you have to isolate y:

9x=8y+3 |-3

9x - 3=8y | :8

9/8x - 3/8=y or

y=9/8x - 3/8, so the slope m is 9/8

the last step is to determine b:

you use the x and y coordinates of the given point and m:

the point is (-9,7)

x= -9

y=7

m=9/8

y=mx + b

plug it in:

7=9/8*(-9) + b

7= -81/8 + b |+81/8

56/8 +81/8=b

137/8=b

So the line containing the given point and parallel to the given line is:

y = 9/8x + 137/8

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the main point for the second question is: to find a line that is perpendicular to another line, the slope of the line, that is perpendicular is -1/m (m is the slope of the other line):

6x+7y=2 |-6x

7y= -6x+2 | :7

y=-6/7*x+2

that means m= -6/7

the slope of the perpendicular line is +7/6

the rest works like in the first question

Good luck

In the first one, you change the equation so that you have y alone on one side and then the number in front of x will be your slope. plug in the x and y of your ordered pair and have the letter b instead of 3/8. solve for b. you have your answer.

the second one is the same.

In the third one you would do the same thing, but make the slope (m or he number before x) have the opposite sign before plugging in x and y. I hope you can figure your homework out.