SOLUTION: Use the method of substitution to solve the system (x^2+y^2=17) (x+y=1)

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Question 601259: Use the method of substitution to solve the system (x^2+y^2=17) (x+y=1)
Answer by mananth(16946) About Me  (Show Source):
You can put this solution on YOUR website!
x%5E2%2By%5E2=17
(x+y)=1
y= 1-x
x%5E2%2B%281-x%29%5E2=17
x%5E2%2B1-2x%2Bx%5E2=17
2x%5E2-2x%2B1=17
2x%5E2-2x-16=0
/2
x%5E2-x-8=0

Find the roots of the equation by quadratic formula

a= 1 , b= -1 , c= -8

b^2-4ac= 1 + 32
b^2-4ac= 33
%09sqrt%28%0933%09%29=%095.74%09
x=%28-b%2B-sqrt%28b%5E2-4ac%29%29%2F%282a%29
x1=%28-b%2Bsqrt%28b%5E2-4ac%29%29%2F%282a%29
x1=( 1 + 5.74 )/ 2
x1= 3.37
x2=%28-b-sqrt%28b%5E2-4ac%29%29%2F%282a%29
x2=( 1 -5.74 ) / 2
x2= -2.37
When x= 3.37 y = -2.37
When x= -2.37 y=3.37
m.ananth@hotmail.ca