Homeowork help .. new to this ...

Joined
Dec 1, 2009
Messages
5
Hello,

I am in grade nine math class .... we have a really bad teacher, who recently informed us that he failed his math classes in his highschool years .... He writes notes for us .. gives us homework , and DOES not explain anything to us ..... Ive never been the best at math .. it takes me mroe time to learn new things in math then others .... This year, i dont get anything .. I cant even do my homework because our teacher doesnt teach us anything ... But i do attempt to try .... I need help. I dont even know what the topic is that were learning, so im not sure if im in the rights section to this wesite .. i just signed up .... i think i am learning equations with fractions as coefficients ..... I tried to do my homeowkr looking at his notes and examples .. but my friend in grade 10 math .. tol me that he had the wrong anwers to the examples .. no wounder i cant get the homework .. any way ... here are some of the questions . and what i attemped to do ... I am really not sure weatherim doing it right or wrong ..

1.) 2m+9
----------
5 = 17 *for this one .. i did it trying to mirror my teachers example .. but when I put my final answer back into the equation.... it was wrong
here is what I did ...

2m+9=85
2m+9-9=85-9
2m = 76 below this line is a line .. for a fraction
2 2
m=38

This one I have no clue whatso ever what to do ..

x+1 x-2 below this is an line .. for a fraction
3 = 2

Thank you so much ... Sam ...
 
Hi,
sometimes having a bad maths teacher is ok,
what you learn through your own efforts,
if you apply yourself will stick with you better.

I don't see anything wrong with your work for the first one...
{2m+9}/5 = 17
m=38 is correct

For the second one
{x+1}{x-2}/3 = 2 is that the problem?

{x+1}{x-2} = 3(2) = 6
What two numbers, where one is bigger than the other by 3, multiply to give 6 ?
I give up,
so we must solve the quadratic equation.

{x+1}{x-2} = 6

How do you multiply these out ?
3(4) = 12 and (2+1)(6-2) is 12 since 2+1 is 3 and 6-2 is 4.
This is 2(6-2) +1(6-2) which is 2(6) +2(-2) +1(6) +1(-2) = 12-4+6-2 =12
So, you multiply out factors with x term by term.

{x+1}{x-2} = x{x-2}+1{x-2} = x[sup:1qla77ij]2[/sup:1qla77ij]-2x+x-2 = x[sup:1qla77ij]2[/sup:1qla77ij]-x-2
and this is 6.
So you have x[sup:1qla77ij]2[/sup:1qla77ij]-x-2 = 6
Next... if they are equal, if we subtract them the answer is zero.

x[sup:1qla77ij]2[/sup:1qla77ij]-x-2-6 = 0, so x[sup:1qla77ij]2[/sup:1qla77ij]-x-8 = 0.

If we could write this as a multiplication (factorise), we could use the fact that
two numbers multiplied give zero, so either one could be zero.
That's not easy here, so you can use the "abc" formula for ax[sup:1qla77ij]2[/sup:1qla77ij]+bx+c = 0

x is {-b+sqrt(b[sup:1qla77ij]2[/sup:1qla77ij]-4ac)}/2a and {-b-sqrt(b[sup:1qla77ij]2[/sup:1qla77ij]-4ac)}/2a

so x is {1+sqrt(1-4{-8})}/2 and {1-sqrt(1-4{-8})}/2
 
"x+1 x-2 below this is an line .. for a fraction
3 = 2"

I think what you have is (x + 1)/3 = (x - 2)/2

(x - 2) • 3 = (x + 1) • 2
3x - 6 = 2x + 2
3x - 2x - 6 = 2x - 2x + 2
x - 6 = 2
x - 6 + 6 = 2 + 6
x = 8

Does this make sense?
 
Yes that does make sense .. and yes that was what I was trying to write .. I was unsure of how to write fractions and equations on the computer ... Just one questions though .. What is that dot you put on the first line ??? Thanks
 
habs_fanatic_chick_6 said:
Yes that does make sense .. and yes that was what I was trying to write .. I was unsure of how to write fractions and equations on the computer ... Just one questions though .. What is that dot you put on the first line ??? Thanks

That's short-cut for "multiplied by" (or "times").
 
Sam, is your first equation:

2m+9 / 5 = 17 ?

/ means divided by

1/ multiply both sides by 5 to cancel out the denominator of 5... so far... now 2m+9 = 85

2m + 9 = 85

subtract 9 from both sides

2m = 76

divide both sides by 2

m = 38 !

well done!
 
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