College Algebra help » solving Equations and also Inequallities » Equations with an ext than One change

Solve for X:

 

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Explanation:

In

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, if we"re solving for x, we first need to obtain the "x" term isolated. We do this by individually 3 indigenous both sides so:

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becomes

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Now we division both political parties by 8

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Re-written the price becomes

 

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Larry has a handful of dimes and also quarters. In total, he has 14 coins through a worth of $2.60. How countless of every coin does he have?


Explanation:

Since this difficulties has 2 variables (D-dimes and Q-quarters) we require 2 equations. Since Larry has actually 14 coins, the first equation can be composed as:

 

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The value of those coins amounts to $2.60 or 260 cents. If Dimes space worth 10C and also quarters room 25C, the following equation have the right to be written as

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To fix this write both equations on optimal of each other

 

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Now we eliminate 1 variable by multiplying 1 equation by the lowest usual denominator (as a negative) and including the equations together.

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becomes

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adding the equations

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-----------------------------------

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now we solve for Q.

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Since we know Q, now we plug it earlier in come an equation and also find D

 

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Larry has 6 dimes and 8 quarters

 

 


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Example concern #3 : Equations With more Than One variable


Solve for X and Y because that the complying with pair of equations


Possible Answers:
Correct answer:

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Explanation:

There are two ways to resolve for x and also y in a pair that equations. One way is to add the two equations together and eliminate one of the variables. It may be necessary to main point one equation by a confident or an unfavorable number in order come cancel out among the variables. The second method is come pick one of the equations and solve for among the variables. Let"s pick the optimal equation and also solve because that x:

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Now substitute x top top the other (bottom) equation:

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Now, due to the fact that we know the value of y, usage either equation and also "plug in" the worth of y:

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To examine your answers, you have the right to plug in both answers to either equation, and since they room equations, if both sides space equal, your answers space correct.


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Example concern #4 : Equations With much more Than One variable


Solve for X and Y v the following collection of equations:


Possible Answers:
Correct answer:

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Explanation:

There are 2 methods to settle this collection of equations. First, you deserve to solve for one of the variables, then substitute that worth for the variable in the various other equation. The other way is to add the equations together (combine), and to execute this, periodically multiplying among the equation by a positive or negative number is required. Let"s see exactly how we deserve to do this:

Remember the an essential is to add the two equations together and eliminate one of the variables:

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Look in ~ the x and y variables. Notice how if we added the two equations together, us can remove the x variable and also we deserve to thus settle for y:

So now, add the 2 equations together:

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We gained this buy including 4y + 2y and 22+2. Now let"s division the equation by 6, therefore we have the right to solve the worth of y.

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so

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Now plug the known value the y right into either that the 2 equations. Let"s use the optimal equation. Remember that doesn"t issue which equation you choose to deal with for x:

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If you desire to double-check your answers, just insert your worths of x and y into the equation, and remember that since it"s one equation, both sides will be equal.