SOLUTION: please help me solve this equation Solve. y^2=1-x^2 x-2y=4 (4, 0) and (0, -2) No Solution (0, 4) and (-2, 0) (4, 2) and (0, 0) thanks in ad

Algebra ->  Finance -> SOLUTION: please help me solve this equation Solve. y^2=1-x^2 x-2y=4 (4, 0) and (0, -2) No Solution (0, 4) and (-2, 0) (4, 2) and (0, 0) thanks in ad      Log On


   

Question 891632: please help me solve this equation
Solve.
y^2=1-x^2
x-2y=4

(4, 0) and (0, -2)

No Solution

(0, 4) and (-2, 0)

(4, 2) and (0, 0)

thanks in advance
Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
y^2=1-x^2
x-2y=4

Your system, system%28y%5E2=1-x%5E2%2Cx-2y=4%29

x=2y%2B4;
y%5E2=1-%282y%2B4%29%5E2
y%5E2=1-4y%5E2%2B16y%2B16----MISTAKE HERE!
y%5E2=1-%284y%5E2%2B16y%2B16%29----FIXED MISTAKE!
y%5E2=1-4y%5E2-16y-16
0=1-5y%5E2-16y-16
-5y%5E2-16y-15=0
highlight%285y%5E2%2B16y%2B15=0%29
Discriminant, 16%5E2-4%2A5%2A15=256-300=highlight%28-44%3C0%29
-
NO REAL SOLUTION BECAUSE DISCRIMINANT IS NEGATIVE.

(EDIT: Fixed Mistake)