Showing posts with label My Algebra.com posts. Show all posts
Showing posts with label My Algebra.com posts. Show all posts

Friday, May 29, 2015

if tan(theta) = -3 and cos(theta) < 0, then tan(theta/2) = ?

tan%28theta%29=opp%2Fadj=-3%2F1
so
hyp=sqrt%281%5E2%2B%28-3%29%5E2%29=sqrt%2810%29
so
sin%28theta%29=%283%2Asqrt%2810%29%29%2F10
cos%28theta%29=-sqrt%2810%29%2F10 (we take the negative case because cosine is negative for this example)
now
tan%28theta%2F2%29=sin%28theta%29%2F%281%2Bcos%28theta%29%29
Therefore...

tan%28theta%2F2%29=%28%283%2Asqrt%2810%29%29%2F10%29%2F%281-sqrt%2810%29%2F10%29
which simplifies to
%28sqrt%2810%29%2B1%29%2F3

Monday, May 25, 2015

Sunday, May 24, 2015

The element lawrencium has a half-life of 10 hours. What fraction of 1 ounce of lawrencium will remain after 4 days 4 hours?

4 days and 4 hours is 4(24)+4 = 100 hours 
so our quantity is halved 10 times over the time period: 

Q=Q%5B0%5D%2A%281%2F2%29%5E10 

Q=%281%2F1024%29%2AQ%5B0%5D


so its 1/1024 oz

Find the twentieth term of the arithmetic sequence with a1 = 15 and d = 4.

For an arithmetic progression we use the formula:

a%5Bn%5D=a%5B1%5D%2B%28n-1%29%2Ad

n=20, a1=15, d=4


a%5B20%5D=15%2B%2820-1%29%2A4

a%5B20%5D=15%2B19%2A4

a%5B20%5D=91

:)

how can i decompose this partial fraction(4x^3)/(x^3-x^2)

This is not a "proper" decomposition problem. Typically the degree of the denominator is greater than the degree of the numerator...
but...we can still simplify...
notice that this expression can be factored:
%284x%5E3%29%2F%28x%5E3-x%5E2%29=%28%28x%5E2%29%284x%29%29%2F%28%28x%5E2%29%28x-1%29%29
from here we notice that by polynomial long division (don't know how to show using this editor) that:
x%2F%28x-1%29=1%2B1%2F%28x-1%29
so our expression simplifies to...

%284%2B4%2F%28x-1%29%29

:)

find a if a(a-8)=20

a(a-8)=20
a%5E2-8a-20=0
%28a-10%29%28a%2B2%29=0

so a= 10 or a=-2

Is it a function?

given the relation {(-4,-2),(1,-4),(3,0),(4,3)} determine if this relation is a function
a. yes it is a function because each x value has only one y value
b. no it is not a function because -4 appears twice
c. no it is not a function because each x value does not have a unique y value
d. yes it is a function because each x value is unique



by definition of a function:
a. yes it is a function because each x value has only one y value

Find dy/dx at the point (0, 1), if y^5 = (x + 2)^4 + e^xln y − 15 Amy.

Saturday, May 23, 2015

Friday, January 16, 2015

Solve: 8|2-9p|-2=14


8|2-9p|-2=14
8|2-9p|-2+2=14+2
8|2-9p|=16
8/8|2-9p|=16/8
|2-9p|=2 

case 1)
2-9p=2
-9p=0
p=0 

case 2)
2-9p=-2
-9p=-4
p=4/9