Question about substitution and elimination problem?

Rosa Luciano

New member
2/3y-6=-1/2x
1/2y-3x/4=0

how would i do substitution for this problem

2x+2y-8=0
2x+1=y

i have y=2x+1

so can x=0 and y=1 I'm very confuse .

What about elimination method for y-3x=-2
2y-6x=4

Can x=-4 than y=-4??
 
(2)/(3)*y-6=-(1)/(2)*x
(1)/(2)*y-(3x)/(4)=0

Multiply -(1)/(2) by x to get -(x)/(2).
(2)/(3)*y-6=-(x)/(2)

Multiply (2)/(3) by y to get (2y)/(3).
(2y)/(3)-6=-(x)/(2)

Multiply (1)/(2) by y to get (y)/(2).
(y)/(2)-(3x)/(4)=0

Since -6 does not contain the variable to solve for, move it to the right-hand side of the equation by adding 6 to both sides.
(2y)/(3)=6-(x)/(2)

Move all terms not containing y to the right-hand side of the equation.
(2y)/(3)=-(x)/(2)+6

Multiply each term in the equation by 3.
(2y)/(3)*3=-(x)/(2)*3+6*3

Simplify the left-hand side of the equation by canceling the common factors.
2y=-(x)/(2)*3+6*3

Simplify the right-hand side of the equation by simplifying each term.
2y=-(3x)/(2)+18

Divide each term in the equation by 2.
(2y)/(2)=-(3x)/(2)*(1)/(2)+(18)/(2)

Simplify the left-hand side of the equation by canceling the common factors.
y=-(3x)/(2)*(1)/(2)+(18)/(2)

Simplify the right-hand side of the equation by simplifying each term.
y=-(3x)/(4)+9

Replace all occurrences of y with the solution found by solving the last equation for y. In this case, the value substituted is -(3x)/(4)+9.
(-(3x)/(4)+9)/(2)-(3x)/(4)=0

Divide each term in the numerator by the denominator.
-(3x)/(4)/(2)+(9)/(2)-(3x)/(4)=0

Convert the multiple level fraction to a set of regular fractions by multiplying by the reciprocal of the denominator.
-(3x)/(8)+(9)/(2)-(3x)/(4)=0

Find the LCD (least common denominator) of -(3x)/(8)-(3x)/(4)-(9)/(2).
Least common denominator: 8

Multiply each term in the equation by 8 in order to remove all the denominators from the equation.
-(3x)/(8)*8-(3x)/(4)*8=-(9)/(2)*8

Simplify the left-hand side of the equation by canceling the common factors.
-9x=-(9)/(2)*8

Simplify the right-hand side of the equation by simplifying each term.
-9x=-36

Divide each term in the equation by -9.
-(9x)/(-9)=-(36)/(-9)

Simplify the left-hand side of the equation by canceling the common factors.
y=-(3x)/(4)+9_x=-(36)/(-9)

Simplify the right-hand side of the equation by simplifying each term.
x=4

Replace all occurrences of x with the solution found by solving the last equation for x. In this case, the value substituted is 4.
y=-(3(4))/(4)+9

Multiply -3 by 4 in the numerator.
y=(-3*4)/(4)+9

Multiply -3 by 4 to get -12.
y=(-12)/(4)+9

Move the minus sign from the numerator to the front of the expression.
y=-(12)/(4)+9

Reduce the expression -(12)/(4) by removing a factor of 4 from the numerator and denominator.
y=-3+9

Add 9 to -3 to get 6.
y=6

This is the solution to the system of equations.
y=6
x=4

Hope I explained thoroughly enough.


2x+2y-8=0
2x+1=y
You must use subsitution to solve for BOTH x and y.
x=1
y=3


Can x=-4 than y=-4??
Yes.
 
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