Anyone good with Algebra???

mommy2owen wrote: So, my brother was sent home with a packet of Algebra work to do, and I have no idea how to help him! I was never good at Algerba.


Here is a problem he has been having trouble with:

Josh hit a baseball straight up into the air. The equation below describes the height of the ball (h), in meters, as a function of time (t) in seconds.

h(t)= -908t squared + 30t = 1.5

anyone got a clue?

Maddie&EthansMom replied: Sorry, I suck at Algebra.... Never could pass that darn class in college.

mckayleesmom replied: nope.....I suck.....I slept in class.

Kaitlin'smom replied: its been sooo long I was great at it, but right now i am way to tried to think sorry

mckayleesmom replied: Ok...someone needs to answer this question...I have been staring at it for 10 minutes....It helps if I know what Im trying to figure out...kwim...for example...little willy threw the ball up such and such high in such and such seconds...yadda yadda......Im clueless....I have no clue how I got out of school.

mommy2owen replied: We thought we got it. But then looked again and realized that we totaly forgot a number! I have no clue what I am doing!

mckayleesmom replied: I remember what I use to do...Does he have a textbook with the answers in the back of the book? I would look up a question with similar format to see how they did it. Our books would either give us the odd number answers or the evens and our teacher always assigned us the opposite of what was in the book. And we never had tests...so I was good to go.

mommy2owen replied: He has the textbook. But the answer's are torn out.

Teachers these days, dont trust their students to do anything themselves!

mckayleesmom replied: ..Its because of students like me.

mommy2owen replied:
I did the same thing!

Josie83 replied: Okay let mehave a try . .. I wasn't too bad at it in school but a bit ruty now! Give me a minute xx

Josie83 replied: Okay I have been trying to figure it out and its the question that I am having trouble with. is that exactly how it is worded in the book? Because, I can't seem to make sense of the answer. I know you have to balance it all out and divide and all the rest of it, but something about it just doens't make sense to me. . . . if you have shorthanded it, would you be able to long hand it up again Thanks xx

mckayleesmom replied: Josie..I think that where it says =1.5 should be +1.5....I looked it up and it didn't have an anwswer for any kind of equation like that.......look at my post to courtney

MommyToAshley replied:
Is the second = sign supposed to be a different sign or is it actually an = sign?

Anyways, a good way I used to remember the rule for which order you do the calculations was to remember "My Dear Aunt Sally". The first letter of each word stands for M=Multipy, D=Divison, A=Addition, S=Subtraction. So, you would do muliplications first and then Division, and so on

I can help you out with the equation, but can you check on the second = sign, I believe it should be something else?

GavinsMommy replied: i had a 100 in algebra...i can help too if the equation is right...

mckayleesmom replied: I think its suppose to be +1.5....Heres what I looked up

Simplifying
h(t) = -908squared + 30t + 1.5

Multiply h * t
ht = -908squared + 30t + 1.5

Reorder the terms:
ht = 1.5 + -908adeqrsu + 30t

Solving
ht = 1.5 + -908adeqrsu + 30t

Solving for variable 'h'.

Move all terms containing h to the left, all other terms to the right.

Divide each side by 't'.
h = 1.5t-1 + -908adeqrst-1u + 30

Simplifying
h = 1.5t-1 + -908adeqrst-1u + 30

Reorder the terms:
h = 30 + -908adeqrst-1u + 1.5t-1

mommy2owen replied:
Yes, that is exactly how it is! Very confusing if you ask me.

mommy2owen replied: Opps! When my brother typed the problem he did make a mistake and put an = instead of a +. So you guys were right!

PascosGirl replied: You do most algebra problems in this order:

Please Excuse my dear Aunt Sally which stands for:

Parenthesis
Exponents
Muliplication
Division
Addition
Subtraction

Alice replied: OK_ I'm a math teacher.

What you were given was the equation of the path the ball would follow. The reason everyone is having such trouble is that there's no question attached; what do you want to find?

The 2nd = sign should probably be either a + or a -; have him check.

They're probably looking for one of two things: the maximum height of the ball or the time it takes for it to hit ground.

To find max height: Tell him to find the axis of symmetry (x=-b/2a) In this case the a= -908 (the amount of x squared) and b=30 (the amount of x) so the axis of symmetry would be x= -30/(-1816) (the 1816 is 2x908). I don't have a calculator handy but it's in the neighborhood of .02omething... I'll use .02 as the example.
Take that value of x and plug it into the equation to find the height. So it's
-908(.02)squared (square it before you multiply) -30(.02) +/- 1.5 (depending on the correct equation. That will give the height in meters at its highest.

To find out how long it takes to hit ground, 2 methods:
a) if it takes .02 seconds to go up, it takes another .02 seconds to come down. So it takes a total of .04 seconds total.
Solve the original equation. It can't be factored, so he would need the quadratic equation. But plan a) is much easier.

Hope that helped!!

Edited because I made a dumb I'm-so-tired-I-can't-think-error!

mommy2owen replied: He got help with the problem from a friends father, who is an Algebra 2 teacher!

But thanks for all of your help! I'm glad someone knows how to do this stuff!