How do you solve x^2+y^2=153, y=-4x? Precalculus Solving Systems of Two Equations Solving by Substitution 1 Answer ali ergin Dec 10, 2016 x={-3,+3} Explanation: x^2+y^2=153 y=-4x (y^2)=(-4)^2 (y)^2=16x^2 x^2+16x^2=153 17x^2=153 x^2=153/17 x^2=9 x={-3,+3} Answer link Related questions What is a system of equations? What does it mean to solve a system of equations by substitution? How do I use substitution to find the solution of the system of equations c+3d=8 and c=4d-6? How do you write a system of linear equations in two variables? How does a system of linear equations have no solution? How many solutions can a system of linear equations have? What is the final step of completing a solve by substitution problem? How do I use substitution to find the solution of the system of equations 4x+3y=7 and 3x+5y=8? How do I use substitution to find the solution of the system of equations y=2x+1 and 2y=4x+2? How do I use substitution to find the solution of the system of equations y=1/3x+7/3 and... See all questions in Solving by Substitution Impact of this question 7121 views around the world You can reuse this answer Creative Commons License