Transcript Document

Solving Quadratic Equations
by Finding Square Roots
Remember: Linear equation
is x to the first power
ax+by=c
Quadratic equation: is x to the
second power
Standard Form:
2
ax +bx+c=0
a0
Find Solutions to ax2+c=0
(Get x2 alone in form
2
x =d)
2
x =d
Once you get
take the
square root of both sides to
get x.
3 Results
1. x2=d If d is a positive number,
then you have 2 solutions
x d
2.
2
x =d
If d=0 then there is only
one solution
x=0
3. x2=d If d is a negative number,
there is no solution
(Can’t take sq. root of a negative)
Examples:
2.
1.
x2=5
x2=4
x  4
2
x  2
x  5
2
x 5
x can be + or -,
when squared it is
positive
Solve:
2
4x +
100 = 0
-100 -100
4x2 = -100 (divide both sides by 4)
x2 = -25
NO Solution
2
3x -99
=0
2
3x = 99
2
x = 33
x   33
Two Solutions
The surface area of a
cube is 150ft2. Find the
length of each edge.
x
x
2
6s
SA =
1st
2
150 = 6s
DIVIDE
2
25 = s
x
Sides of the cube are 5 ft.
You can’t have a negative
length.
5  s
BY 6
Watch out below!
A construction worker on the top floor
of a 200 foot tall building accidentally
drops a heavy wrench. How many
sections will it take to hit the ground?
The formula d=rt is used when the
speed is constant. However, when an
object is dropped, the speed
continually increases.
Use the formula:
h = -16t2 + s
h = final height of object
t = time
s = starting height of object
h = -16t2 + s
0 = -16t2 + 200
-200 = -16t2
12.5 = t2
√12.5 = t
About 3.54 seconds.