Solve the simultaneous equations: x^2+y^2=36 ; x=2y+6
Substitute x in terms of y into the first equation:
(2y+6)2+y2=36
Use FOIL to expand the brackets
4y2+24y+36+y2=36 => 5y2+24y=0
y(5y+24)=0 => y=0 or y=(-24)/5
Substitute these values of y into the second equation to find x
when y=0, x=2*0+6 => x=6
when y=(-24)/5, x=2*(-24)/5+6 => x=-3.6
DB
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