Solve systems using method of substitution, Algebra

Example   Solve following systems.

(a)    3x - y = 7

                2x + 3 y = 1

Solution

Thus, it was the first system that we looked at above.  Already we know the solution, although it will give us a possibility to verify the values that we wrote down for the solution.

Now, the method says that we have to solve out one of the equations for one of the variables.  Which equation we select and which variable that we select is up to you, however usually it's best to pick an equation & variable which will be easy to deal with. It means we should try to ignore fractions if at all possible.

In this case it seem like it will be actually easy to solve the first equation for y thus let's do that.

                                              3x - 7 = y

 Substitute this into the second equation.

                   2 x + 3 (3x - 7 ) = 1

It is an equation in x which we can solve so let's do that.

2x + 9 x - 21 =1

11x = 22

x = 2

Thus, there is the x portion of the solution.

At last, do not forget to go back and determine the y portion of the solution. It is one of the more common mistakes students make in solving out systems.  To so it we can either plug the x value in one of the original equations & solve for y or we can only plug it into our substitution which we found in the initial step. That will be simple so let's do that.

                                          y = 3x - 7 = 3 ( 2) - 7 = -1

Thus, the solution is x = 2 and y = -1 as we noted above.

Posted Date: 4/8/2013 5:18:30 AM | Location : United States







Related Discussions:- Solve systems using method of substitution, Assignment Help, Ask Question on Solve systems using method of substitution, Get Answer, Expert's Help, Solve systems using method of substitution Discussions

Write discussion on Solve systems using method of substitution
Your posts are moderated
Related Questions
how can you model the addition of polynomials with algebra tiles

1) The goal of the first questions is to implement some code that performs calibration using the method described in the book; by first computing a projection matrix, and then deco


A company makes and sells notebook computers. The company’s cost function in thousands of dollars is C(x) = 0.3x + 100, and the revenue function in thousands of dollars is R(x) = 0


find the average rate of change of the function f(x)=4x from X1=0 to x2=6

Alice bought a round-trip ticket to fly from Baltimore to Chicago on SuperAir for $250. That was $16 more than she would have on Jet Airlines, which only offered a one-way fair. Ho

Now we need to discuss graphing functions. If we recall from the earlier section we said that f ( x ) is nothing more than a fancy way of writing y. It means that already we kno

Question 1 (Multiple Choice Worth 1 points) (05.02) Choose the equivalent system of linear equations that will produce the same solution as the one given below. 4x - 2y = 6 2x +

how do I change 0.68 to a fraction or mixed number