9x^2-4=0,(3x+4)(3x-4)=0,3x+4=0, 3x=-4, x1=-1 1/3,3x-4=0, 3x=4, x2=1 1/3; 5x^2-20=0,x^2-4=0,(x+2)(x-2)=0,x+2=0, x1=-2,x-2=0, x2=2; y^2-10/65=0,y^2-2/13=0,y^2=2/13,y1=-√(2/13),y2=√(2/13); 0,64-y^2=0,(0,8+y)(0,8-y)=0,0,8+y=0, y1=-0,8,0,8-y=0, y2=-0,8; z^2-7=0,(z+√7)(z-√7)=0,z+√7=0, z1=-√7,z-√7=0, z2=√7; 11-z^2=0,z^2=11,z1=-√11,z2=√11; 4x^2+x=0,x(4x+1)=0,x1=0,4x+1=0, 4x=-1, x=-1/4; 3x-2x^2=0,x(3-2x)=0,x1=0,3-2x=0, 2x=3, x=1,5.