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Simultaneous equations

x2 + 2xy = 5 x + y = 3

Make y the subject of the second formula. y=3-xSubstitute y into the first one: x^2+2x(3-x)=5x^2+6x-2x^2=5      =》  -x^2+6x-5=0 or   x^2-6x+5=0(x-5)(x-1)=0   which means x=1 or x=5When x=1  y=2When x=5  y=-2
01 December 2018
x^2 +2xy=3 marked as euation 15x+y=3 marked as equation 2 from eq 2 we have y=3-5x substituting in equation 1 we obtain x^2 +2x(3-5x)=3x^2 +6x-10x^2=3 9x^2 -6x+3 =0  solving this equation quadratic formula we have x=[1+i(2)^1/2]÷2 or x=[1-i(2)^1/2]÷2
16 December 2018
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