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CAS: Concern in solution - compsystems - 04-16-2017 03:38 PM Hi, I have a concern when the next system is resolved for the second case (x=11/4 and y=1/4), fails, why? cplx1:=(x^2+2*y^2)+(x*i+y*i); cplx2:=(x*y+7)+3*i; expr1:=(cplx1 = cplx2); answer1 := csolve(expr1,x); → {(1/2)*(y+√(-7*y^2+(-6*i)*y+27+12*i)-i), (1/2)*(y-√(-7*y^2+(-6*i)*y+27+12*i)-i)} wolfram // By property of equality of complex numbers on expr1 (a+b*i = c+d*i) <=> a=c & b=d {(x^2+2*y^2) = (x*y+7), (x+y) = 3} answer2 := solve({ re(expr1), im(expr1)}, {x,y}); → {[1,2],[11/4,1/4]} // (x=1 and y=2) or (x=11/4 and y=1/4) test for (x=1 and y=2) subst(expr1,{x = 1,y = 2}) → (9+3*i) = (9+3*i) evalb(Ans) → true // Xcas cmd but subst(answer1(1),y=2); → 1 // x=1 // ok test for (x=11/4 and y=1/4) subst(expr1,{x = 11/4,y = 1/4}) → ((1/8)+(121/16)+3*i) = (123+48*i)/16 evalb(Ans) → true but subst(answer1(2),y=1/4.); → -2.5-i // x=-2.5-i ?? -> x = 11/4 PHP Code: //evalBool |