Wednesday

August 20, 2014

August 20, 2014

Posted by **jojo** on Thursday, March 5, 2009 at 8:25pm.

x2+y2=18

x+y=4

- math b -
**Damon**, Thursday, March 5, 2009 at 8:26pmDo you mean the circle

x^2+y^2 = 18 ?

- math b -
**jojo**, Thursday, March 5, 2009 at 8:34pmyes

- math b -
**Damon**, Thursday, March 5, 2009 at 8:36pmMaking that assumption, we are looking for where the straight line:

y = -1x + 4

which has a slope of -1 and goes through (0,4) and (4,0)

hits the circle with center at the origin and radius 3 sqrt 2 which is about 4.24

Sketch a graph so we will get an idea of how the solution should look.

So

substitute y = -x + 4 into the circle

x^2 + (-x+4)^2 = 18

x^2 + x^2 - 8 x + 16 = 18

2 x^2 -8 x -2 = 0

x^2 - 4 x -1 = 0

x = (1/2)[ 4 +/- sqrt (16 +4)]

x = (1/2) [ 4 +/- 2 sqrt 5]

x = 2 +/- sqrt 5

find the y for each of those x values

**Related Questions**

System of equation - solve algebraically x^2 + y^2 = 16 x - y = 4

math - solve the following system of equations algebraically or graphically for ...

PreCalculus - PLEASE HELP ME ASAP!!!!!!!!!!!! :) I really need to remember on ...

Math - 1/2z - 1/4w = 1/6 1/2z + 1/4w = 1/6 Solve the system of equations ...

math b - solve each system of equations algebraically: x^2+y^2=18 x+y=4

MATH - Solve system of equations algebraically. 1. 3x-3y=24 and 2x+5y=-37 2. -9x...

[math] - How do I solve this equation algebraically? 1/2x + 2/3 = 1/8x - 3/2 ...

Math - Solve the equation algebraically for x where 0 </ x <2pi. sin (x-(...

Precalculus - Please help me. Solve the system algebraically. 16)y=x^3+x^2 y=3x^...

MATH - Solve the equation algebraically for x where 0 </ x <2pi. sin x = ...