一个物体从高空下落,经过4秒落地.已知第一秒下落的距离是4.9米,以后每一秒下落的距离都比前一秒多9.8米.这个物体在下落前距地面多少米?
直接写得数．24×= += = 1﹣25%= ÷18=24×（+）= ×= 4.3×99+4.3= = =
直接写出得数×= ÷4= 7﹣= 1.2×=×= ÷= ÷2= 18÷=
直接写得数：7.2×= 1÷= = ×0.3=10÷0.1×10÷0.1= 3= += == 18=
计算下面各题×= ×8= 6×= 27﹣= 22÷= ×=54÷= += 1﹣= ﹣= 16×= ÷=
直接写得数．3×= 1÷= ÷= +=0÷= ×= ÷= 6×=
= 
+
= 
= 1﹣25%= 
÷18=
+
）= 
×
= 4.3×99+4.3= 
= 
=
×
= 
÷4= 7﹣
= 1.2×
=
×
= 
÷
= 
÷2= 18÷
=
= 1÷
= 
= 
×0.3=
= 
+
= 
=
= 18
=
×
= 
×8= 6×
= 27﹣
= 22÷
= 
×
=
= 
+
= 1﹣
= 
﹣
= 16×
= 
÷
= 1÷
= 
÷
= 
+
=
= 
×
= 
= 6×
=
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