# Thread: Math Help..

1. ## Math Help..

1)

5./ 2 (7./8+5./3)

2)
-3x-13>-4,D={Integers}

3)

(-2)
----
-4

5)

(2010^-4)(410^9)
--------------------
3,20010^-3

6)

-(-{-[-(-64)]})

7)
Simplify:

a-5ab+2a+ab+2ab

8)

Greatest Common Factor:
8cdw^5-10c^6dw^10

9)

3x(2xy+4y)

10)

Solve:

x-10=49

2. Originally Posted by autopimp
2)
-3x-13>-4,D={Integers}

3)

(-2)
----
-4
2)
$\displaystyle -3x-13>-4$
$\displaystyle -3x-13+13>-4+13$
$\displaystyle -3x>9$
$\displaystyle \frac{-3x}{-3}<\frac{9}{-3}$ Note the change in the > here!
$\displaystyle x<-3$.

3) $\displaystyle \frac{-2}{-4}=\frac{-2}{2*-2}=s$.

What do the decimal points in the first problem mean?

-Dan

3. Originally Posted by autopimp
5)

(2010^-4)(410^9)
--------------------
3,20010^-3

6)

-(-{-[-(-64)]})
5) $\displaystyle \frac{2010^{-4}410^9}{320010^{-3}}=\frac{320010^3410^9}{2010^4}$

The prime factorizations of these are:
$\displaystyle 2010=2*3*5*67$
$\displaystyle 410=2*5*41$
$\displaystyle 320010=2*3*5*10667$

So:
$\displaystyle \frac{320010^3410^9}{2010^4}=\frac{(2^33^35^310667 ^3)(2^95^941^9)}{2^43^45^467^4}$
$\displaystyle \frac{2^{12}3^35^{12}41^910667^3}{2^43^45^467^4}= \frac{2^85^841^910667^3}{3*67^4}$

I'm not sure what else to do with it.

6) $\displaystyle -(-{-[-(-64)]})=(-1)^5*64=-64$.

-Dan

4. Originally Posted by autopimp
7)
Simplify:

a-5ab+2a+ab+2ab

8)

Greatest Common Factor:
8cdw^5-10c^6dw^10
7) First combine the like terms:
$\displaystyle a-5ab+2a+ab+2ab$
$\displaystyle (a+2a)+(-5ab+ab+2ab)=3a-2ab$
Each term has a common a, so factor the a:
$\displaystyle 3a-2ab=a(3-2b)$.

8) $\displaystyle 8cdw^5-10c^6dw^{10}$
I don't know what you mean by "greatest common factor," I suspect you simply mean to factor the expression.
So, there is a common 2, one c, one d, and five w in each term:
$\displaystyle 8cdw^5-10c^6dw^{10}=2cdw^5(4-5c^5w^5)$.

-Dan

5. Originally Posted by autopimp
9)

3x(2xy+4y)

10)

Solve:

x-10=49
9) $\displaystyle 3x(2xy+4y)=3x*2xy+3x*4y=6x^2y+12xy$.

10)
$\displaystyle x-10=49$
$\displaystyle x-10+10=49+10$
$\displaystyle x=59$.

-Dan

6. Originally Posted by autopimp
1)

5./ 2 (7./8+5./3)
I'm not sure of what the decimal points are for but my best guess is:
$\displaystyle \frac{5}{2} \left (\frac{7}{8}+\frac{5}{3} \right)$
$\displaystyle \frac{5}{2} \left (\frac{7}{8} * \frac{3}{3} + \frac{5}{3} * \frac{8}{8} \right )$
$\displaystyle \frac{5}{2} \left ( \frac{21}{24} + \frac{40}{24} \right )$
$\displaystyle \frac{5}{2} \left ( \frac{21+40}{24} \right )$
$\displaystyle \frac{5}{2} \left ( \frac{61}{24} \right )$
$\displaystyle \frac{5*61}{2*24}=\frac{305}{48}$.

-Dan