Tuesday, May 27, 2014
Wednesday, May 21, 2014
assuming that cos(theta)=2/7 for an acute angle theta, find sin(theta)
Given:
the fastest way is to use the pythagorean identity:
which simplifies to...
the fastest way is to use the pythagorean identity:
which simplifies to...
Simplify with out using a calculator the square root of 704.
factorization can be done by successive division by the prime numbers:
Now we employ the properties of square roots:
:)
Now we employ the properties of square roots:
:)
One number is 5 greater than another number. their sum is equal to 5 times their difference. Find the numbers.
1)x=y+5
2)x+y=5(x-y)
2)x+y=5(x-y)
1) tells us x-y=5
therefore we can repalce x-y with 5 in 2)
therefore we can repalce x-y with 5 in 2)
new system:
x+y=25
x-y=5
x-y=5
adding the two equations...
2x=30
x=15
so...
so...
y=10
Solve the compound inequality |3x-9| < 15 AND |2x-3| > 5
1)
-15 < 3x-9 < 15
-15+9 < 3x < 15+9
-6 < 3x < 24
-2 < x < 8
(-2,8)
2)
2x-3 < -5 or 2x-3 > 5
2x < -2 or 2x > 8
x < -1 or x > 4
(-oo,-1)U(4,oo)
intersection:
(-2,-1) U (4,8)
-15 < 3x-9 < 15
-15+9 < 3x < 15+9
-6 < 3x < 24
-2 < x < 8
(-2,8)
2)
2x-3 < -5 or 2x-3 > 5
2x < -2 or 2x > 8
x < -1 or x > 4
(-oo,-1)U(4,oo)
intersection:
(-2,-1) U (4,8)
{x + y = 9, 1/x + 1/y = 1/2} Find x and y.
leads to
but
so
this means
which leads to
so that or
then we can see:
{ (3,6), (6,3) }
Is this sequence geometric or arithmetic or neither: 3,5,9,15 ?
9-5=4
5-3=2
so it is not arithmetic
15/9=5/3
so it is not geometric either
... so neither
5-3=2
so it is not arithmetic
15/9=5/3
so it is not geometric either
... so neither
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