SOLUTION: Solve the system of equations using substitution. x2 + y2 = 169 x + y = 17

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Question 548386: Solve the system of equations using substitution.
x2 + y2 = 169
x + y = 17
Answer by mananth(16946) About Me  (Show Source):
You can put this solution on YOUR website!
x^2+y^2=169
x+y=17
x=17-y
(17-y)^2+y^2=169
189-34y+y^2+y^2=169
20-34y+2y^2=0
/2
10-17y+y^2=0
y^2-17y+10=0
Find the roots of the equation by quadratic formula

a= 1 ,b= -17 ,c= 10

b^2-4ac= 289 + -40
b^2-4ac= 249
x=%28-b%2B-sqrt%28b%5E2-4ac%29%29%2F%282a%29 15.78
x1=%28-b%2Bsqrt%28b%5E2-4ac%29%29%2F%282a%29
x1=%28-12%2B21%29%2F%2812%29
x1=( 17 + 15.78 )/ 2
x1= 16.39
x2=( 17 -15.78 ) / 2
x2= 0.61
x=16.39 so y=0.61
x=0.61 so y=16.39
m.ananth@hotmail.ca