3 Answers

Equation of a Straight Line
The equation of a straight line is usually written this way:
y = mx + bWhat does it stand for?
Slope (or Gradient) Y Intercept y = how far up
x = how far along
m = Slope or Gradient (how steep the line is)
b = the Y Intercept (where the line crosses the Y axis)
How do you find "m" and "b"?
 b is easy: just see where the line crosses the Y axis.
 m (the Slope) needs some calculation:
m = Change in Y Change in X Knowing this we can work out the equation of a straight line:
Example 1
m = 2 1 = 2
b = 1 (where the line crosses the YAxis)Therefore y = 2x + 1 With that equation you can now ...
... choose any value for x and find the matching value for y
For example, when x is 1:
y = 2×1 + 1 = 3
Check for yourself that x=1 and y=3 is actually on the line.
Or we could choose another value for x, such as 7:
y = 2×7 + 1 = 15
And so when x=7 you will have y=15
Example 2
m = 3 1 = –3
b = 0
This gives us y = –3x + 0
We do not need the zero!Therefore y = –3x Example 3: Vertical Line
What is the equation for a vertical line?
The slope is undefined ... and where does it cross the YAxis?In fact, this is a special case, and you use a different equation, not "y=...", but instead you use "x=...".
Like this:
x = 1.5Every point on the line has x coordinate 1.5,
that’s why its equation is x = 1.5Rise and Run
Sometimes the words "rise" and "run" are used.
 Rise is how far up
 Run is how far along
And so the slope "m" is:
m = rise run You might find that easier to remember

There are three functions that give us a straight line when we graph them.
y=mx+b
This function can be graphed using the rise and run method where b is your starting point and m is your rise/running number. M can be expressed as a whole, 3, or a fraction, 3/4. Whole numbers will always run 1. Fractions the numerator is your rising number and the demoninator is your running number. If m is positive then you run to the right, if its negitive you run to the left.
y= a number
This is a horizontal line at that value. It translates into all x values have that y as an answer
x= a number
This is a vertical line at the vaule. It translates to all y values of have the same x.
Suggested reading…
Simplify expressions with surds into the form a + b3
Be warned this topic is Chuck Norris hard. Make sure you've done the related topics below before you try and get your head round this one...

So if you put a square root sign around a number that is not a square number, then what you have written is a surd.
e.g. √10 is a surd, because 10 is not a square number. √9 is not a surd, because 9 is a square number, so you can write √9= 3
Even if the number under the square root sign is not a square number, it can still be simplified.
Write the starting number as a product of two new numbers, where one of them is a square number (e.g. 45 > 9 x 5). Take the root of the square number, and write it outside of the root sign
e.g. √45 = √(9×5)=3√5
Follow the links below to see how this topic has appeared in past exam papers
Other Relates Topics…
Related Questions

0Votes1Answer

0Votes1Answer

0Votes1Answer

0Votes1Answer

0Votes1Answer

0Votes1Answer

0Votes1Answer

0Votes1Answer

0Votes1Answer

9Votes10Answers