3x²-10x+3= 0;
D = 100 - 4 * 3 * 3 = 100 - 36 = 64
x1 =( 10 - 8)/6 = 2/6 = 1/3
x2 = (10+8)/6 = 3;
71x² + 144x + 4 = 0;
D = 20736 - 4 * 71 * 4 = 20736 - 1136 = 19600
x1= (-144-140)/142 = -2;
x2= (-144+140)/142 = -4/142
9x²-30x+25= 0;
D = 900 - 4 * 9 * 25 = 0;
x1 = 30/18 = 5/3