抛物线顶点为(2.5,4)
则设抛物线方程为y=-a(x-2.5)2+4,
令x=0有
1.6=-6.25a+4;
a=3.2/6.25=18/5*4/25=72/125
令y=0,
则0=-72/125(x-2.5)2+4
(x-2.5)2=125/18,
x=±5/6√10+2.5=±2.63+2.5取大于2.5的解,即x=5.13(米)
抛物线顶点为(2.5,4)
则设抛物线方程为y=-a(x-2.5)2+4,
令x=0有
1.6=-6.25a+4;
a=3.2/6.25=18/5*4/25=72/125
令y=0,
则0=-72/125(x-2.5)2+4
(x-2.5)2=125/18,
x=±5/6√10+2.5=±2.63+2.5取大于2.5的解,即x=5.13(米)