5x²-9x=18
x²-(9/5)x=18/5
x²-(9/5)x+(9/10)²=(18/5)+(9/10)²
[x-(9/10)]²=441/100
x-(9/10)=±(21/10)
x=(9/10)±(21/10)
x1=3,x2=-6/5