my geometrey blog

Sunday, April 1, 2012

how do we review inequalities

inequalities is pretty basic.Having an inequality problem like 2x+10<14 is the same as 2x+10 = 14.
We want to get x by it self so we substrate 10 from both sides.
We get 2x < 24 now, we divide 2 from both sides we get x <12 on a number line the twelve will have a open circle and the line will go to the left side.
Now lets try a harder one for example 2x+3y<15
First we try to get y by it self so we substrate 2x from both sides we are left with 3y<-2x+15
Now divide by 3 to get y<2/3x+5

x < n when the sign is like this you have open circle and we shade to the left.
x < n when the line is under the less then sign then the circle is closed with the shade going to the left.
x > n when the sign is like this one the circle is open with the shaded line going to the right.
x > n and finally when the greater sign has the line under the circle is shaded and the shaded line goes to the right.

now that you guys have a understanding check out the link below for more problem:

http://teachers.henrico.k12.va.us/math/hcpsalgebra1/Documents/4-4/solvcompinequ.htm

and for more help check out the two other links:

Sunday, March 25, 2012

How do we slove quadratic equations using the qudratic formula

the formula for a quadratic equation is ax^2 +bx +. we need to know this before we can solve it with quadratic formula. so lets get started
Ex://

x^2-6x+5=0
the first step is find out what are the a,b,and c
A=1,B=-6,C=5
now we place them in the quadratic formula x = -(-6)+/-√((-6)^2-4(1)(5))/2(1)
we will do solve (-6)^2-4(1)(5)
(-6)(-6)=36
-4*5=-20
36-20=16 we get √16 = 4(perfect square)
-(-6)=6
6+/-4/2(1)
6+4/2=5
6-4/2=1
x=5,1
3x^2-6x+4=0
-(-6)+/-√((-6)^2-4(3)(4))/2(3)
6+/-√(36-12(4))/6
6+/-√(-12)/6
we finished (check out the http://jesuslikesmath.blogspot.com/2012/03/how-do-we-use-quadratic-formula.html)

here are some links for help:

How do we use the quadratic formula

to understand how to use a quadratic formula we first have to know what is a quadratic formula. the letter in this equation are from the quadratic equation
ax^2 + bx +c.

Ex://
x^2+2x-15=0
A= 1
B= 2
C= -15

x= -2+/-√(2^2-4(1)(-15))/2(1)
we will multiply -4(1)(-15) to get 60
we and 2^2+60 and get 64(this is the discriminant)
-2+/-√(64)/2(1)
-2+8/2=3
-2-8/2=5
x = 3,5

if the discriminant is more the 0 then there is more then one solution
if the discriminant is equal to 0 then there is only one solution
if the discriminant is less then 0 then there is no solutions

hope this was helpful for more help check these links below: