Posted by mikey123 on Friday, October 31, 2008 at 11:45pm.
Ok, I'm going to try to explain this and let you come to the answer yourself. Feel free to post it so I can check your work and see what you don't understand.
The equation of the line is y = mx + b, where m represents the slope of the line, b is the y intercept (that is, a value on the line where x is equal to 0) and (x,y) are your coordinates.
In order to find the equation of the line, you have to find m or b. In this question, you have to find b given m and a point (x,y).
So you substitute your given values into the equation y = mx + b and solve for b by multiplying m and x and subtracting (or adding depending on the sign) that product from y.
so is mx the 6/7 or the (5,-7) see this is where it gets confusing for me, I know that The equation of the line is y = mx + b,but how do you find either mx and b
m and x are different values. x is a point on the graph (naturally, on the x axis) and m is the slope. m = 6/7 so your slope is 6/7 and x is 5. y is -7. (x,y) = (5,-7).
You're given m(6/7), x(5), and y(-7). You have to find b by substituting it into the equation and isolating b.
Oh, and once you find b you plug in the values of m and b into the equation and leave x and y for there can be any arbitrary point where you can find y for any values of x and vice versa.
okay but I need to know what the steps are, for example I have 6/7 and (5,-7) what do I do with these I know they are used to find mx and b, maybe you can show me the steps needed this way once I see how it is done perhaps I can use the same method for other problems.
Given:
m = 6/7
x = 5
y = -7
y = mx + b
*plug in your given numbers*
-7 = (6/7)(5) + b
*multiply m and x*
-7 = (30/7) + b
*isolate b by subtracting (30/7) from both sides*
-7 - (30/7) = b
*solve for b*
-79/7 = b
Sam thanks I have done three since this one and I now understand.