Find the points of intersection of line y=3+2x with the circle x^2+y^2=50?

1 Answer
Apr 14, 2017

x=-4.305 and y=-5.61 or x=-1.905 and y=-0.81

Explanation:

We have y=3+2x and x^2+y^2=50. Putting first in second, we get

x^2+(3+2x)^2=50

or x^2+9+4x^2+12x=50

or 5x^2+12x-41=0

and using quadratic formula x=(-12+-sqrt(144+4×5×41))/(2×5)= (-12+ sqrt964)/10

x=(-12+-31.05)/10

For -4.305 or -1.905

Aand y=-4.305×2+3=-5.61 or -1.905×2+3=-0.81

i.e. x=-4.305 and y=-5.61 or x=-1.905 and y=-0.81

These indicate two points at which line y=3+2x cuts circle x^2+y^2=50.

graph{(3+2x-y)(x^2+y^2-50)=0 [-20, 20, -10, 10]}