# Need Help!

• Mar 5th 2006, 08:27 AM
autopimp
Need Help!
I have few probs i need to help with here are cupple i did them on photoshop heres the link to it CLICK HERE TO SEE THE PROBS
• Mar 5th 2006, 10:13 AM
ThePerfectHacker
Problem 3]
$\frac{x-3}{4}-\frac{x}{7}=7$
Multiply by Common Denominator to get,
$28\cdot\frac{x-3}{4}-28\cdot\frac{x}{7}=28\cdot 7$, thus,
$7(x-3)-4x=196$
Thus,
$7x-21-4x=196$
Thus,
$3x-21=196$
Thus,
$3x=217$
Thus,
$x=\frac{217}{3}=72.\bar 3$
• Mar 5th 2006, 10:38 AM
ThePerfectHacker
Problem 4]
$\frac{m^4(n^{-3})^2}{(m^{-2})^{-3}n^0} \left(\frac{m^{-4}n^8}{n^8m^{-2}} \right)^2$
Open parantheses,
$\frac{m^4n^{-6}}{m^6n^0}\cdot \frac{m^{-8}n^{16}}{n^{16}m^{-4}} \right)$
Use rule of exponents,
$m^{-2}n^{-6}m^{-4}n^0$
Use rule of exponents again ( $n^0=1$),
$m^{-6}n^{-6}$
Q.E.D.
• Mar 5th 2006, 10:40 AM
ThePerfectHacker
Problem 5]
$f(-\frac{2}{3})=\frac{-\frac{2}{3}}{2}=-\frac{1}{3}$
Q.E.D.
• Mar 5th 2006, 10:45 AM
topsquark
Quote:

Originally Posted by autopimp
I have few probs i need to help with here are cupple i did them on photoshop heres the link to it CLICK HERE TO SEE THE PROBS

Problem 2.

Solve by substitution:
$2x+3y=7$
$x-2y=7$

In the substitution method we solve one of the equations for one unknown and plug it into the other...this creates an equation with only one unknown in it. I tend to pick the simplest variable to solve for. In this case that looks to be the x in the second equation.

So solving the second equation for x I get:
$x=2y+7$

Plugging this value of x into the first equation I get:
$2(2y+7)+3y=7$.

I'll let you take it from here. You may plug this value of y into any of the original equations, or more simply, into your x equation. I get (x,y) = (5,-1).

-Dan
• Mar 5th 2006, 10:57 AM
earboth
Quote:

Originally Posted by autopimp
I have few probs i need to help with here are cupple i did them on photoshop heres the link to it CLICK HERE TO SEE THE PROBS

Hello,

to problem nr. 6: Transform the quotient into a product:
$\frac{2x-10}{x^2-25}\ \cdot \ \frac{x^2-4x-5}{x^2-2x-15}$
factorize all numerators and denominators:
$\frac{2(x-5)}{(x+5)(x-5)}\ \cdot \ \frac{(x+1)(x-5)}{(x+3)(x-5)}$
simplify and you'll get:
$\frac{2(x+1)}{(x+5)(x+3)}$

Greetings

EB
• Mar 5th 2006, 11:03 AM
earboth
Quote:

Originally Posted by autopimp
I have few probs i need to help with here are cupple i did them on photoshop heres the link to it CLICK HERE TO SEE THE PROBS

Hello,

to problem nr. 8:
Calculate the roots partially:
$3\cdot \sqrt{32}-5\cdot \sqrt{50}-8 \cdot \sqrt{45} + 7\cdot \sqrt{20}=$
$3\cdot 4\sqrt{2}-5\cdot 5\sqrt{2}-8 \cdot 3\sqrt{5} + 7\cdot 2 \sqrt{5}=$
$-13 \sqrt{2}-10 \sqrt{5}$

Greetings

EB