x2+20x+91
x¹×40×¹+91
x¹+¹×40+91
x²×40+91
40ײ+91
x2 + 20x + 91=0
D= b2-4ac= 400 - 364=36
x1= -20 +6 / 2*1= -14 / 2= -7
x2= -20 - 6 /2*1= -26/2= -13
1 (x +7) (x+13)
