Math Problems:

Math Problems:Solving quadratic equation

For some questions, you have some conditions that you don’t know. So you can use a symbol such as “n” to set up several equations according to the questions. Then solve the equations that you set up in order to get the value for “n”.

Here is an example:
If you spend five dollars on shoes, two dollars on gloves and after that you still have four dollars left. How many dollars do you have originally?
Ans: Make the amount of money you have originally “n”, so:
n-5-2=4
n=4+5+2=11
Thus, you have 11 dollars originally!!

Solving math problem-quadratics equation, and quadratics formula derivation:
Example 2:
ax^2+bx+c=0
1x^2+4x+4=0=
(x+2)^2
0=x+2
x=-2

quadratics formula derivation:
ax^2+bx+c=0 divide both side by a
x^2+b/ax+c/a=0, then put c/a to the other side
x^2+b/ax=-c/a,
x^2+b/ax+(b/2a)^2=(b/2a)^2-c/a
(x+b/2a)^2=b^2/4a^2-c/a
x+b/2a=(+/- (b^2-4ac)/4a^2)^(-2)
x= (b+_(b^2-4ac))^(-2)/2a