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m23chris
solve using row reduction: 4x+9y=1 3x+7y=1
row reduction=elimination?
im not exactly sure what you mean
im trying to find x and y
http://en.wikibooks.org/wiki/Linear_Algebra/Row_Reduction_and_Echelon_Forms
@.Sam. ,you are right
First make x the same 4x+9y=1 times 3 3x+7y=1 times 4 ------------------------------------- 12x+27y=3 12x+28y=4 ======== -y=-1 y=1 4x+9y=1 4x+9(1)=1 4x+9=1 Solve for x
well row reduction deals with matrices and elimination deals with systems of equations, so they're slightly different, but they get you the same answer.
i need to solve it using the matrix
see here @m23chris : http://www.math.hmc.edu/calculus/tutorials/linearsystems/
we never really did it like this its hard to understand
4x+9y=1 3x+7y=1 4 9 1 3 7 1 1 9/4 1/4 (1/4)*R1 3 7 1 1 9/4 1/4 0 1/4 1/4 R2 - 3*R1 ---> R2 1 9/4 1/4 0 1 1 4*R2 1 0 -2 R1 - (9/4)*R2 ---> R1 0 1 1 So the solutions are x = -2 and y = 1
so youre dividing by 4 in the first row
yes in the third step
ok i get it now but i have 2 more questions involving 3 rows using the matrix can you help me?
sure, just make a new question and let me know about it