math/algebra
posted by Diana
solve each of the following systems by substitution.
16) 5x 2y = 5
y  5x = 3
20) 8x 4y = 16
y = 2x  4
28) 4x 12y = 5
x + 3y = 1
Step one: Solve on of the equations for one of the variables.
y=2x4
Step two:Substitute the expression for the variable found in step one into the other equation.
8x4(2x4)=16
Step three:Solve the equation from step two to find the value of one variable.
Use the distributive property
8x4(2x4)=16
8x8x+16=16
x+16=16
16 16
x=0
Step four:Substitute the value found in step three in any equation containing both variables to find the value of the other variable.
y=2x4
y=2(0)4
y=04
y=4
step five: check the proposed solution in the orginal system.
8(0)4(4)=16
0+16=16
16=16
The equation is equal, so it is correct.
#28
4x12y=5 x+3y=1
+x +x
3y=x or 3y=x
4(3y)12y=5 4x12(5)=5
12y12y=5 4x60=5
y=5 +60 +60
4x=65
x=65/4
4(65/4)12(5)=5
260/4  60=5
65  60 = 5
5 = 5
it's correct
I hope I helped
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