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## #1 2015-03-06 07:28:45

PatternMan
Member
Registered: 2014-03-08
Posts: 199

### Basic rearranging formula

When you rearrange for a it doesn't matter if there are two t's on the other side. However if I wanted to isolate t I would have to get them both on one side and factor right? In this case is there any way to isolate t?

Last edited by PatternMan (2015-03-06 07:30:41)

"School conditions you to reject your own judgement and experiences. The facts are in the textbook. Memorize and follow the rules. What they don't tell you is the people that discovered the facts and wrote the textbooks are people like you and me."

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## #2 2015-03-06 07:35:03

zetafunc
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Registered: 2014-05-21
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## #3 2015-03-06 07:44:35

PatternMan
Member
Registered: 2014-03-08
Posts: 199

### Re: Basic rearranging formula

but zetafunc there are 3 unkown variables in this equation? Usually when you use the quadractic formula they only have an x unknown.

"School conditions you to reject your own judgement and experiences. The facts are in the textbook. Memorize and follow the rules. What they don't tell you is the people that discovered the facts and wrote the textbooks are people like you and me."

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## #4 2015-03-06 10:48:07

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

### Re: Basic rearranging formula

You should be able to isolate t in this case but that is not always possible.

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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## #5 2015-03-06 21:09:44

bob bundy
Registered: 2010-06-20
Posts: 8,445

### Re: Basic rearranging formula

hi PatternMan

The same algebraic equality may be either an equation or a formula.  The same rules of algebra apply to both.  If this was an equation you wouldn't be able to solve it as there are too many unknowns.

But it is a formula.  You treat all the letters except the 'subject' as if you do know their values.  If you re-arrange a formula, you make a new letter into the subject.  You then assume that all the other letters have known values.

Because t squared occurs in the formula, it is a quadratic in t and you'd have to use factorisation, the quadratic formula or the method of completing the square to get t as the subject.

This looks like one of the equations* of motion in Newtonian mechanics.  The minus indicates a deceleration of magnitude 'a'.  There are other equations that can also be used, so, depending on what letters you 'know', it may be possible to get t using another of the equations*.

* They are called the equations of motion, but in view of what I've said above, they should really be called the formulas of motion.

Bob

Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob Bundy

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