math
posted by karly .
Solve using elimination method 7x+5y=56;21x2y=168

thsi is how i would do it
lets say equation 1 will be 7x + 5y = 56
and equation 2 is 21x  2y = 168
nothign can cancel out if you llok at the equation so what i would do is multiply equation 1 by a negative 3 that way the 7x becomes a positive 21x to cancel out(but you have to multpliy everything in the equation by 3 not just the 7x)
so you will have;
21x 15y = 168
now add the two equation together
(21x  15y= 168) + (21x  2y=168)
notice the x and the total on the right side of equal sign cancels leaving you with :
17y=o y=0 since 0 dvide by anything is still zero now choose any of your original equation and plug in 0 for y and solve for x
Respond to this Question
Similar Questions

Algebra
Solving system of linear equations by using the apropiate method name the method and the x,y coordinates 1)X=4y+8 2x8y=3 2)3x7y=6 elimination method 2x+7y=4 (2,0) 3)5x2y=12 elimination method 3x2y=2 (7,23/2) 4)9x8y=42 elimination … 
math
Can someone please check my work? Solve using substitution method 1. 3x+2y=12 x=526y answer:40.8 I am pretty sure that one is wrong. Solve using elimination method 2. 2r7s=31 7r+2s=24 answer: (230/53,468/53) 3.3x+4y=3 6x+8y=6 
Algebra
How do I solve for the elimination method: 5x + 3y= 7 and 7x  2y =13 (step 1); 10x + 6y =14 and 21x 6y = 39 ( step 2), 31x/31= 25/31, x= 25/31 (step 4). But after that I get lost. Can somebody help me out please. 
math
can someone please help me with this elimination methods problem? 
math elimination method
elimination method really confuses me. solve by elimination method 5r 3s = 17 3r + 5s =17 A. solution is ______ (ordered pair, integer or fraction) B. Infinitely many C. No Solution 
Algebra/Elimination method
Solve using the elimination method. If the system has no solution or an infinite number of solutions, state this. 27x  18y = 180 9x + 6y = 60 
Math
4x3y=5 Solve { 5y+7=3x using the method of elimination. 
math
Please solve the system with the elimination method. Explain each step as it is performed. 5y = x 2x  3y = 7 Would the elimination method have been your first choice to solve this problem? 
Algebra 1
bobpursey, In this problem you helped me with earlier: Solve using any appropriate method. y = 2×  5, y = ½× + 1 Substitution, substitute for y. 2×5=½ × + 1 3/2 x=6 x=4 y= 2*45=3 How did you choose which method you were going … 
Math
y=3x+2 4x2y=8 Solve using Elimination method