The line 2x+3y=1 intersects the curve x(x+y)=10 at A and B. Calculate the coordinates of A and B.

2 answers

solve the first for y
3y = 1-2x
y = (1-2x)/3 , now sub that into the other equation

x(x+(1-2x)/3) = 10
x(3x+1-2x)/3 = 10
x(x+1)) = 30
x^2 + x - 30 = 0
(x+6)(x-5) = 0
x = -6 or x = 5

if x = 5, y = (1-10)/3 = -3
if x = -6 , y = (1 + 12)/3 = 13/3

So A = (5,-3) and B is (-6, 13/3)

(of course it doesn't matter who is called A or B)
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