The number of ordered pairs (x,y) of real numbers that satisfy the simultaneous equations x+y2=x2+y=12 is
4
x+y2=x2+y=12x+y2=x2+yx−y=x2−y2⇒x=y,x+y=1When x=yx2+x=12x2+x−12=0x2+4x−3x−12=0(x+4)(x−3)=0x=−4,3(3,3)(−4,−4)When y=1−xx+(1+x)2=12x2−x−11=0x=1±√1+442 for two values of x there are two values of y. So four pairs.