## Tuesday, August 17, 2010

### SUMMARY OF LINEAR EQUATIONS ...

ANONYMOUS - 17th August 2010
1. Today we reconsidered the linear equation & the general form of a linear equation is y = mx + c
2. where by the m refers to the GRADIENT
3. where c is the Y-INTERCEPT (or the value of y when x = 0)
4. m is POSITIVE when as x increases, y also increases
5. m is NEGATIVE when as x increases, y will decrease
6. m is ZERO when as x changes, y is constant (HORIZONTAL LINE)
7. m is undefined when x is constant and y changes (VERTICAL LINE)
8. X-INTERCEPT would be equal to -c / m ... (or the value of x when y = 0)
NOTE - c (or the constant in all the equation) is always the y-intercept, even for equations such as y = ax^2 + bx + c ...
Why do you think this is so? (HINT - look at point (3) above)

Prove point (8) for yourself ...

1. y=ax² + bx +c

at the y intercept
x=0

y=a(0)²+b(0)+c
= c

y intercept = (0.C)

2. C is not always the y intercept since if the it was 1/x, it would be undefined so c cannot be the y intercept
y=1/x+4
=undefined