Solving by Substitution Method

Algebra 1 Help : In the algebra there are several system of equations that have the several variable so values of these variables are solved by Substitution method. When there are several equations in the system then these are solved using some predefined steps of substitution method to solve algebra linear equations that are as follows :
( a ) There are 1 variable for one equation as x ,y,z means if there are three variable given in an equation then there are also three equations to find the value of these variables .
( b ) For solving the missing variable substitute the expression into the other equation .
( c ) When find the value of a variable that find into the step (b) then put it into the first equation and find the answer .
( d ) Cross check the solution .
The above steps are using to find the values of the variable in the given example :
-p +q = 1
2 p+q = -2
step no ( a ) : Find one equation for one variable there are two variable p and q
-p+q = 1
-p+p+q = 1+p (add the +p for both side of equation to find the one variable )
q = 1+p or q = p+1 .
step no ( b ) : For solving the missing variable substitute the expression into the other equation as
2 p+q = -2
put the value of q by the step no ( a ) into this equation
2 p+(1+p) = -2
2 p+p+1 = -2
3 p+1 = -2
Solve the value of p by subtracting the 1 from both side of equation
3 p+1–1 = -2–1
3p = -3
Divide the both side of equation by 3
3p/3 = -3/3
p = -1
Step no ( c ) : Find the value of q by putting the value of p into one of the equation
q = p+1
q = -1+1
q = 0
step no ( d ) : Cross check the answer
put both the values into each equation
-p+q = 1 2p+q = -2
-(-1)+0 = 1 2(-1)+0 = -2
1 = 1 -2 = -2


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