Transcript Formulas - NW LINCS

Formulas
3-2-1
Formulas
• Formulas appear in almost any profession.
• A formula is an expression where the
variables and result have a specific
meaning.
• In the formula P=2w+2l the w and l are
measurements and the result, P, is the
perimeter of a rectangle.
Steps:
• Copy the pattern the formula makes.
• Insert the known numbers for the
variables.
• Simplify.
Formulas
• You don’t need to memorize these
formulas.
• In fact you may not even need to
understand what the formula means.
• You do need to be able to put the values in
the proper place and simplify.
Formula A=lw
• Where w is width and
l is length
• Example: A=(7)(3)
• =21 in2.
3 in.
7 in.
A= ½ h(b1+b2)
• where h is the
perpendicular height
between the bases
and b1 and b2 are the
bases.
• A= ½ (4)(4+10)=28
in2.
10 in.
5 in.
4 in.
4 in.
5 in.
V=4/3πr3
• where r is radius and
π is pi.
• Example:
• radius 3 mi
• V=4/3π(3)3=36 π
• =113.9mi3.
SA= πr2+πrs
13 m
12 m.
5 m.
• where r is radius, π
is pi, and s is the
length of the slant of
the cone.
• Example:
• SA= π(5)2+π(5)(13)
• = 90π
• 282.74
I=Prt
• where I is interest, P is the principal, r is the annual rate,
and t is the time in years.
• A car is sold for $15000 with simple interest at 12% for a
period of 5 years. How much interest is paid? How
much total is paid back? What is the monthly payment?
• I=Prt=(15000)(.12)(5)=$9000 (Write 12% as a decimal.)
• Total = 15000+9000=$24000 (Add the principle to the
interest.)
• Monthly Pmt. = 240000/12=$400
• (Divide the total by the number of months.)
Celsius to Fahrenheit
• What is 80C in Fahrenheit?
9C
F
 32
5
9(80)
F
 32  176 F
5
Fahrenheit to Celsius
• What is 80F in
Celsius?
5  F  32 
C
9
5 80  32 
C
 26.67C
9
Mean or average
• Where n is the number of numbers to be
averaged and x1, x2, x3 and so on are the
numbers to be averaged.
x1  x2  ...  xn
A
n
• Janet got a 458, 500, 482, 440, and 500
on her GED tests. What was her average
score? A=476
458  500  482  440  500
A
5
Distance
• where d is the distance between two
points (x1. y1) and (x2, y2).
d
x
1
 x2    y1  y2 
2
2
• Find the distance between (-2, -3) and
(8,3).
d
 2  8    3  3 
2
2

 100  36  136  11.66
 10    6 
2
2
Quadratic Formula
• The solution for an equation
• 0=ax2 + bx + c the solution is
b  b  4ac
x
2a
2
• I know big and hairy.
• What are the solutions for:
• 0=2x2-9x+10 a =2, b=-9 and c=10
(9)  (9) 2  4(2)(10) 9  81  4(2)(10)
x

2(2)
4
9  81  80 9  1 9  1



4
4
4
9 1
9 1
10 5
8

and
for
 and  2
4
4
4 2
4