I don't understand how to write an equation with just a graph. there is no numbers or anything. just a diagonal line through the middle. please help!!
Without seeing the graph, I can't help you get the exact answer, but I can give you some tips that might help you.
1. Since you stated that the graph is a diagonal line, I know that you are looking for a linear equation. Linear equations can be written in the from y = mx + b.
To get the exact equation, we need to find the values of m and b (you will keep th1.e y and x in the final answer).
2. The sign on the m value (slope of the line) is determined on whether it goes up or down as you go to the right. If the line goes up to the right, m is positive. If the line goes down to the right, m is negative.
3. Assuming you can see the x and y-axis with hash marks (bold vertical and horizontal lines with small marks evenly spaced along them), you can find the vlaue of m (the slope of the line). The slope is found by counting how much the line moves up or down through a distance moving right to left.
For example, you might find that at one point of the line you are one mark above the x-axis and two marks right of the y-axis. Moving along the line, you may find that you are four marks above the x-axis and four marks above the y-axis. The slope is found by comparing the change in height (1 mark up goes to 4 marks up) and the change in length (2 marks goes up to 4 marks). The ratio is 3 (4-1) to 2 (4-2), so the slope (m) is 3/2.
4. If you can see the where the line crosses the y-axis (bold vertical line), you have your b value.
5. If you can't see where the line crosses the y-axis, you can still find the value of b. Just find a point on the line. Plug the x and y values of the point, along with the slope (m) into the slope intercept formula (y=mx+b) and solve for b.
6. Write the slope intercept form of the equation with the values that you found for m and b.
One other quick tip: If you have hashes on your x-axis and y-axis, but there are no numbers written, assume that each hash represents 1.