SOLVED! ^0^ THANKS SUBHOTOSH KAHN!

Teksunai

New member
Joined
Sep 30, 2009
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3
Good evening everyone! Hope everyone is having an awesome day! ^0^

Anyway, I ish Teksunai and I hash joined caush I need help with some intense math questions. ^_^

I joined honours math which should have been easy enough provided that I actually knew what we were doing (half the stuff that was review we weren't taught at our old school); I'm finally making my way to becoming an awesome 90% student (YEAH!), however, I still have a way to go.

So, I thought to use my resources! ^0^

Anyway, the questions I have trouble with I will write as followed.

Write the standard form of the equation of the line passing through the points M (-4, -2) and N (4,7)

Answer: 9x-8y-29=0

This is my work that I am showing, so it's easier to pinpoint where the problem is. ^_^

From what I have been taught by notes, we first find the slope.

Easy enough.

m=(y2-y1)/(x2-x1)
m=(7-[-2])/(4-[-4])

So it should be
9 over 8 equals the slope, or m=9/8

After that, we should be able to solve b by substituting

So we write it in slope intercept form (y=mx+b) to solve for b

y=9/8x+b

Plug in some coordinates (either M or N; either works)

7=9/8(4)+b

Multiply all terms by 8 to be rid of it the denominator

56=9(4)+8b
56=36+8b
Subtract 36 from both sides.

20=8b

20/8 equals b, or 5/2

So y=9/8x+5/2 should equal

9/8x-y+5/2=0 in standard form.

However, when I check the answer book, it says 9x-8y+20=0.

What am I doing wrong? (To justify 8b becoming 5/2, this is done because all terms are multiplied when you get rid of the denominator; that is what we were taught, even though our previous teacher told us to always go in BEDMAS order, grrr... )

Not only that, but there is help I need to for two other types of questions.

A line passes through (-4, 2) and has the same y-intercept as 2x-y=3. Find its equation.


I have NO IDEA how to begin solving this (What type of equation does it want? What is it asking for) So I would love these people on the board forever if they could also help me with that question (keep in mind the unit is covering Determining Equations of Lines).

Also, ONE MORE THING

Question 20

The smallest of three consecutive odd numbers is represented by x. Find an alebraic expression for their product.


Answer: xcubed+6xsquared+8x


Hooow do you get that... ? o_o'''
(Bear with me and my lack of aesthetic beauty when formulating these questions and answers in improper format; do not know how to write script)

I hope you guys can help and thank you so much for reviewing this! If there is any suggestions you can make both referring to math and the best precise way to get my questions across, please tell me! Thank you!

Lotsa love ~<3~
-Teksunai
 
Re: Determining Equations of Lines (Standard Form), etc

Teksunai said:
Good evening everyone! Hope everyone is having an awesome day! ^0^

Anyway, I ish Teksunai and I hash joined caush I need help with some intense math questions. ^_^

I joined honours math which should have been easy enough provided that I actually knew what we were doing (half the stuff that was review we weren't taught at our old school); I'm finally making my way to becoming an awesome 90% student (YEAH!), however, I still have a way to go.

So, I thought to use my resources! ^0^

Anyway, the questions I have trouble with I will write as followed.

Write the standard form of the equation of the line passing through the points M (-4, -2) and N (4,7)

Answer: 9x-8y-29=0

This is my work that I am showing, so it's easier to pinpoint where the problem is. ^_^

From what I have been taught by notes, we first find the slope.

Easy enough.

m=(y2-y1)/(x2-x1)
m=(7-[-2])/(4-[-4])

So it should be
9 over 8 equals the slope, or m=9/8

After that, we should be able to solve b by substituting

So we write it in slope intercept form (y=mx+b) to solve for b

y=9/8x+b

Plug in some coordinates (either M or N; either works)

7=9/8(4)+b

Multiply all terms by 8 to be rid of it the denominator

56=9(4)+8b
56=36+8b
Subtract 36 from both sides.

20=8b

20/8 equals b, or 5/2

So y=9/8x+5/2 should equal

9/8x-y+5/2=0

You are correct upto here. Just multiply everything by '8' (to get rid of the fraction) and you'll get book's answer.


in standard form.

However, when I check the answer book, it says 9x-8y+20=0.

What am I doing wrong? (To justify 8b becoming 5/2, this is done because all terms are multiplied when you get rid of the denominator; that is what we were taught, even though our previous teacher told us to always go in BEDMAS order, grrr... )

Not only that, but there is help I need to for two other types of questions.

A line passes through (-4, 2) and has the same y-intercept as 2x-y=3. Find its equation.


This is actually very similar to the one above.

First find the y_intercept (0,b)

2x-y=3

y = 2x - 3

so the line (in question) passes through (-4,2) and (0,-3) ... and march on


I have NO IDEA how to begin solving this (What type of equation does it want? What is it asking for) So I would love these people on the board forever if they could also help me with that question (keep in mind the unit is covering Determining Equations of Lines).

Also, ONE MORE THING

Question 20

The smallest of three consecutive odd numbers is represented by x. Find an alebraic expression for their product.


Answer: xcubed+6xsquared+8x


Smallest odd # = x

Next odd number = x + 2

Next odd number = x + 4

Multiply

x(x+2)(x+4)

= x (x[sup:1dq1k5hc]2[/sup:1dq1k5hc] + 6x + 8)

= x[sup:1dq1k5hc]3[/sup:1dq1k5hc] + 6x[sup:1dq1k5hc]2[/sup:1dq1k5hc] + 8x

There..... (feel like Soroban - without his skills of LaTex and patience)



Hooow do you get that... ? o_o'''
(Bear with me and my lack of aesthetic beauty when formulating these questions and answers in improper format; do not know how to write script)

I hope you guys can help and thank you so much for reviewing this! If there is any suggestions you can make both referring to math and the best precise way to get my questions across, please tell me! Thank you!

Lotsa love ~<3~
-Teksunai
 
Re: Determining Equations of Lines (Standard Form), etc

Thank you Subhotosh Khan! I really appreciate your help! ^_^
 
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