# The equation for a straight line

• Jan 6th 2014, 12:19 PM
mstudley89
The equation for a straight line
Sorry if this is in the wrong section I am not sure what this is categorized as. I have a problem regarding the equation for a straight line. I have the following question and solution but im really not sure if I am right to drop the units. Could anyone help please?

· The equation for a straight line is often used in science to find an unknown without reference to a graph. For a set of data for two quatities, A and B, where A is plotted on the x-axis and B on the y-axis, the gradient of the straight line is 2.3 × 104m s−1 and the intercept on the y-axis is 5.8 × 104 m. Using the equation for a straight line (Book 3, Equation 7.12 ) as your starting point, determine the value for A when B = 6.2 × 105 m. Show all your workings and give your answer in scientific notation and to two significant figures.
Y =mx + c

C = 5.8 × 104 m
M= 2.3 × 104m s−1
B = 6.2 × 105 m

6.2 × 105 = 2.3 × 104 A + 5.8 × 104
6.2 × 105 - 5.8 × 104 = 2.3 × 104 A
620000 – 58000= 23000 A
562000 = 23000 A

562000
= A
23000

24.434782608695652173913043478261 = A
A = 24 to 2 significant figures.
• Jan 6th 2014, 01:54 PM
Prove It
Re: The equation for a straight line
What seems to be the trouble? You've done everything correctly...
• Jan 6th 2014, 01:57 PM
mstudley89
Re: The equation for a straight line
I just wanted to check i am correct in dropping all of the units from the equation? would i need to put some back on to the end for my A value?