下面各题怎样简便就怎样算。(1)9.8×1.3+0.98×87 (2)15.4×0.76+1.54×1.4+1.54
简便运算 (1)231×6.2+23.1×208﹣131×27; (2)7﹣1.125+(2.25﹣6); (3)1﹣2+3﹣4+5﹣6+7﹣8+9+97﹣98+99; (4)1++++…+.
计算 3.14×67+8.2×31.4﹣90×0.314 12.65÷12.5÷0.8 (32×0.63×0.95)÷(1.6×21×1.9)
解方程 (1)0.4:0.3=(6﹣x):1.5; (2)2(6+x)=4x+6.
用简便方法计算. 25×1.25×32 (3.75+4.1+2.35)×9.8.
求未知数x ①0.36×5﹣2x=0.4 ②=.