Pre-Algebra
- Thread starter pammyb
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pammyb said:
First step - isplate the variables - that means pu all the terms that has 'x' on one side ofthe equation and put the terma withut 'x' on the other side
3x + 5 = 2x
3x + 5 - 2x = 2x - 2x
3x - 2x + 5 = 0
x + 5 = 0
Isolate again
x + 5 - 5 = 0 - 5
x = - 5
For a quick referesher - go to:
http://www.purplemath.com/modules/solvelin.htm
3x + 15 = 2x
It's like a teeter-totter with the fulcrum at the "=" sign. You must keep it in balance. If you add something to one side, you have to add the same thing to the other side. If you subtract something from one side, you have to subtract the same amount from the other side. If you multiply or divide one side by something, you have to do the same thing to the other side.
Now, then, you want to do whatever is necessary to get one x all by itself on one side of the equation and everything else (no x's) on the other side.
Looking at the equation, let's decide to get all the x's on the left side and all the plain numbers on the right side. This means we have to subtract 15 from the left side. Therefore we must subtract 15 from the right side. This gives us...
3x + 15 - 15 = 2x -15
Now, we simplify by gathering like terms on each side, if possible. On the left side 15 - 15 is 0 giving us...
3x = 2x - 15
We see that we have a 2x on the right side, that we don't want there, so we subtract 2x from the right side AND from the left side. The result is...
3x - 2x = 2x - 15 - 2x
Simplify. (3x - 2x = 1x or simply x and 2x - 15 - 2x = 2x - 2x - 15 = 0 - 15 or simply -15.)
x = -15
Now, we must check our answer. ALWAYS check your answer by substituting what you got back into the original equation in place of the variable.
3x + 15 = 2x
Since we thing x=-15 we plug it into the equation in place of x.
3(-15) + 15 = 2(-15). The question is---Is this true? So we calculate the results on each side of the equation arithmetically.
-45 + 15 = -30 <<< That's on the left side.
2(-15) = -30 <<< That's from the right side.
We see that the sides are equivalent. Therefore, x=-15 satisfies the original equation.
It's like a teeter-totter with the fulcrum at the "=" sign. You must keep it in balance. If you add something to one side, you have to add the same thing to the other side. If you subtract something from one side, you have to subtract the same amount from the other side. If you multiply or divide one side by something, you have to do the same thing to the other side.
Now, then, you want to do whatever is necessary to get one x all by itself on one side of the equation and everything else (no x's) on the other side.
Looking at the equation, let's decide to get all the x's on the left side and all the plain numbers on the right side. This means we have to subtract 15 from the left side. Therefore we must subtract 15 from the right side. This gives us...
3x + 15 - 15 = 2x -15
Now, we simplify by gathering like terms on each side, if possible. On the left side 15 - 15 is 0 giving us...
3x = 2x - 15
We see that we have a 2x on the right side, that we don't want there, so we subtract 2x from the right side AND from the left side. The result is...
3x - 2x = 2x - 15 - 2x
Simplify. (3x - 2x = 1x or simply x and 2x - 15 - 2x = 2x - 2x - 15 = 0 - 15 or simply -15.)
x = -15
Now, we must check our answer. ALWAYS check your answer by substituting what you got back into the original equation in place of the variable.
3x + 15 = 2x
Since we thing x=-15 we plug it into the equation in place of x.
3(-15) + 15 = 2(-15). The question is---Is this true? So we calculate the results on each side of the equation arithmetically.
-45 + 15 = -30 <<< That's on the left side.
2(-15) = -30 <<< That's from the right side.
We see that the sides are equivalent. Therefore, x=-15 satisfies the original equation.
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Subhotosh Khan said:
(Hee, hee)
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Deleted member 4993
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Re:
Thats it - thats it - I am not writing anymore before I had my 10 th cup of coffee :evil: :evil: :evil:mmm4444bot said: