(配方法)10X-4.9X方=0, -4.9x^2+10x=0, x^2-100/49x=0, x^2-100/49x+(50/49)^2=(50/49)^2,
(x-50/49)^2=(50/49)^2, x-50/49=±50/49, x=±50/49+50/49
x1=100/49, x2=0;
(公式法)10X-4.9X方=0, -4.9x^2+10x=0,4.9x^2-10x=0,△=10^2-4*4.9*0=100
x=(10±√100)/2*4.9=(10±10)/9.8,
x1=(10+10)/9.8=100/49, x2=(10-10)/9.8=0