z1=2+3i
z2=5+6i
z1+z2=2+3i+5+6i=(2+5)+(3+6)i=7+9i;
z1-z2=(2-5)-(3-9)i=-3-(-6)i=-3+6i;
z1*z2=(2+3i)*(5+6i)=10+12i+15i+18i²=10+27i+18*(-1)²=10+27i+18=28+27i;
z1/z2=(2+3i)/(5+6i)=(2+3i)*(5-6i)/(5+6i)*(5-6i)=(10-12i+15i-18i²)/5²-(6i)²=10-3i-18/25-36=-(8+3i)/-11=(8/11)+(3/11)i;
z1*
x²-2x+4