Question

use the method of substitution to solve the system
x^2+y^2=20
x+y=1

Answer 1

\[x ^{2} + y^{2}=20,\]
\[x=1-y\]
\[(1-y)^{2}+y^{2}=20\]
\[ 1-2y -y^{2} +y^{2}=20 \]
\[1-2y=20\]
\[-2y=19\]
\[y=-19/2\]

Answer 2

x=1+19/2

Answer 3

Careful:

(1 - y)(1 -y) = 1 - 2y + y^2

Answer 4

Yeah, i know that is equals 1-2y=y^2 and i tried to factor and even complete the square but I am still baffled