Question

A advertising poster in the shape of a triangle has one side that is 5 inches more than the length of the shortest side, and another side that is 3 inches less than twice the shortest side. Find the dimensions of the poster if its perimeter is 26 inches.

Answer 1

Alright. So here's how we do this one:

Answer 2

The perimeter is 26, right?

Answer 3

right

Answer 4

Sorry! My internet died suddenly. Ok, where was I....

Answer 5

5*x

Answer 6

Ah yes...
So we basically know that
Side 1 + side 2 + side 3 = 26

Sound good so far?

Answer 7

yup

Answer 8

6 9 and 11? yay! win!

Answer 9

Okie dokie. We'll let side one be the shortest.

Answer 10

3-x

Answer 11

ok

Answer 12

@woogy: the answer isn't as important as knowing how to do it. I too can just give him the answers in a few seconds. Explaining it takes longer, but I want him to learn how to do it.

Answer 13

Ohhh... my bad. Want the explanations then?

Answer 14

5 inches more than the length of the shortest side

So if we have a side that is 5 inches more than the shortest side, how do we show this?

Answer 15

5+x?

Answer 16

Excellent!

So keep note of that:

Side 1 = x
Side 2 = x+5

Answer 17

Now here's the hard part... how do we show this:
and another side that is 3 inches less than twice the shortest side

Answer 18

It might look scary, but you can do it!

Answer 19

3-x^2

Answer 20

Close. But x^2 would be like saying:

Twice of 4 is 4^2, which is 16 And we know 16 is not twice of 4.

Answer 21

3-x*2

Answer 22

How would you say "two times x", in other words.

Answer 23

Perfect! Or just 3-2x in more conventional terms

Answer 24

side 3 3-2x

Answer 25

Alright, so we have:

Side 1 is x
Side 2 is x+5
Side 3 is 2x-3

Answer 26

Also, I made a mistake. It should have said 2x-3 not 3 -2x

Answer 27

is there a difference
2x-3 or 3-2x?

Answer 28

The reason is because saying 3-2x would mean "it's 3 inches minus twice the size of side 1"

Answer 29

oh ok

Answer 30

x+x+5+2x-3

Answer 31

Yeah. If you plug in a random number, like say 0, the difference is that
2x-3 would equal -3
and 3-2x would equal positive 3.

Answer 32

Good! Now what do the three sides = to?

Answer 33

x+x5+2x-3=26

Answer 34

The key is being able to write the mthematic phrases down correctly... rest is just additions..

Side A (shortest) = x
Side B = x + 5 (add 5 inches to the lenght of the shortest)
Side C = 2x-3 (two time the shorest [which is x], minus 3)
Total = 26 (perimeter)

Put it all in 1 equation...
Side A + Side B + Side C = 26

Now replace the words with numbers...
x + x+5 + 2x-3 = 26

Put all the x's on one side, and the numbrs on the other side...
x + x + 2x = 26 - 5 + 3

Add and simplify...
4x = 24

Isolate the x... To do so we divide by 4 each side, so keep the equation balanced...
(4x)/4 = 24/4
x = 6

Answer 35

Good work woogy.

Answer 36

Am I going too fast or does it make sense?

Answer 37

Excellent, boog1! Now just do the finishing touches.

Answer 38

so 6 is for which side?

Answer 39

When unsure... go back and look at your mathematical phrases

Answer 40

We said
Side A (shortest) = ?
Side B = ?
Side C = ?

Always keep those written somewhere in case you get lost... It happend ot me so many times also that when I got the answer (like x = 6) and I was like... Umm ok, what now?? :P

Answer 41

6,11,9

Answer 42

yep :)

Answer 43

ok! thanks for your help guys!! I will be back again!!!

Answer 44

Sounds great. Hope we made math less scary. It's a beautiful thing when it makes sense.

Answer 45

If you want a tip... I'm a visual kind of person... It reeealllly helps me to draw and write the key infos when solving problems... Like dont be scared to draw the triangle, and write x on a side,x+5 on the other and 2x-3 on the other... no matther how you shape the triangle, its just to help keep things concrete in your head

Answer 46

i used to like math till I started algebra

Answer 47

hahaha ;) I was horrible at algebra because i didn't understand why X was a different thing in each problem... yet we always write x :P

Until a teach said "you have to see X like an empty box... if you're confused, instead of saying X, say "box" "... Then it made things conrete for me

Answer 48

any more problems to solve? maybe the next one you can give it a shot by yourself and we can tell you if you're headed the good/wrong way?

Answer 49

^ I like that!
My problem was remembering when we subtract or when we divide when making an equation. I used to be like:

"Given rt = d, how do you solve for r? Me: Well... subtract r from both sides, and you have t = d-r" Lol

Answer 50

haha, yea... that gets tricky too when priority of equations come into play with parentheses and whatnot... thats why (as done above) i always try to solve equations in 2 steps... first the plus' and minus (+, -) which are easy, then the dividing/multiplying (x, /) once everything is on the right side

Answer 51

Yep. If only I could revisit "highschool me" and tell him this stuff. Gosh, I would have been an Einstein by now. :P

Answer 52

hahahahah!! damn right... I'd nail high school!! :P

Answer 53

Alright, time to find more people to help.. Sorry if i was going too fast earlier, its my 1st time on this site

Answer 54

You did awesome! Take care :)

Answer 55

Nah, I found that you taught it pretty well. You provided an explanation, which is perfect. My method only works live, so while I prefer it to just giving an explanation, it's worthless if the person refuses to answer me. Luckily boog1 actually replies to questions :D

So yeah, your method's perfect. Though if the person's around, you should try to engage them to see where they make mistakes and explain it to them. It might be obvious to the person that "2 times x is 2x" when you tell it to them, but some folks might accidentally think it's "2 + x" or "x times x" if you didn't tell them.

Answer 56

Right right :) gonna work on that :)