Question 971246
same way as for two linear equations.
the substitution, however, should be done with the linear equation rather than the quadratic equation.


for example:


y = x + 1
y = x^2 + 2x + 1


replace y with x + 1 to get x + 1 = x^2 + 2x + 1
subtract x and subtract 1 from both sides of the equation to get:
x^2 + x = 0
factor out the x to get x * (x+1) = 0
solve for x to get x = 0 or x = -1


when x = 0, x + 1 = 1 and x^2 + 2x + 1 = 1
when x = -1, x + 1 = 0 and x^2 + 2x + 1 = 1 - 2 + 1 = 0


you have a common solution of x = 0 and x = -1.


solve for y or x in the linear equation and then use that value to substitute in the quadratic equation.