# Thread: Need Help with a few problems.

1. ## Need Help with a few problems.

Okay we are doing solving linear equations and I am having trouble on a few:

* 4(2n-1)=(3n+9)+8

* x/2 -2=x/5+1

*-2(t-2)+6t=8t -3

*7x+5/8=8x-1/8

Any help would be greatly appreciated.

2. What rules and techniques are available to you?

Have you these?

1) Distributive Proporty of Multiplicatino over Addition
3) Multiplication/Division
4) Gather variables to one side and constants to the other

There may be others. Let's see what you get.

3. okay for the first one i did this:

8n-4=3n+9+8
8n-4=3n+17

But not how do I get all the n's over to one side??

Can i do 8n-4=3n+17
-3n -3n

Which will leave me with 5n-4=17
+4+4
5n=21 divide the 5n but 5 does not go into 21 equally..

What did I do wrong?

4. and for the last one I would do this:

7x+5/8=8-1/8

I would times everything by 8 to get rid of the fractions and it would come out like this:

7x+5=8-1

7x+5=7

then subbtract the 5 and be left with 7x=2 .... but once again I come up with a fraction.

5. Originally Posted by Matt37
okay for the first one i did this:

8n-4=3n+9+8
8n-4=3n+17

But not how do I get all the n's over to one side??

Can i do 8n-4=3n+17
-3n -3n

Which will leave me with 5n-4=17
+4+4
5n=21 divide the 5n but 5 does not go into 21 equally..

What did I do wrong?
Unless you have been told before-hand that the answer is an integer, you have done nothing wrong. Your answer is
$\displaystyle n = \frac{21}{5}$

-Dan

6. Originally Posted by Matt37
and for the last one I would do this:

7x+5/8=8-1/8

I would times everything by 8 to get rid of the fractions and it would come out like this:

7x+5=8-1

7x+5=7

then subbtract the 5 and be left with 7x=2 .... but once again I come up with a fraction.
Not quite. You started with the right idea but you multiplied by 8 wrong:
$\displaystyle 7x + \frac{5}{8} = 8x - \frac{1}{8}$

$\displaystyle 8 \left ( 7x + \frac{5}{8} \right ) = 8 \left ( 8x - \frac{1}{8} \right )$

$\displaystyle 56x + 5 = 64x - 1$

Now take it from here.

-Dan

7. Originally Posted by Matt37

* x/2 -2=x/5+1
$\displaystyle \frac{x}{2} - 2 = \frac{x}{5} + 1$

$\displaystyle 10( \frac{x}{2} - 2) = 10( \frac{x}{5} + 1)$

$\displaystyle 5x - 20 = 2x + 10$

$\displaystyle 3x = 30$

$\displaystyle x = 10$

Originally Posted by Matt37

*-2(t-2)+6t=8t -3
$\displaystyle -2t + 4 + 6t = 8t - 3$

$\displaystyle 7 = 4t$

$\displaystyle t = \frac{7}{4}$

Originally Posted by Matt37

*7x+5/8=8x-1/8
Multiply with 8 straight through

$\displaystyle 56x + 5 = 64x - 1$

$\displaystyle 6 = 8x$

$\displaystyle x = \frac{6}{8} = \frac{3}{4}$

Hope it helps