7.2+2.4-0.4的简便方法

陈庞征21823.6*2.4+36*0.72的简便方法 -
都浅良17765749674 ______ 3.6X2.4+36X0.72 =3.6X(2.4+7.2) =3.6X9.6 =3.6X10-3.6X0.4 =36-1.44 =34.56

陈庞征2182直接写出得数: 7.8+2.2= 5÷2= - 2.4*( - 5)= - 7.2 - 7.2= 8.4÷( - 0.04)= 1 - 0.6+0.4= 1.8+1. -
都浅良17765749674 ______ 7.8+2.2=10 5÷2=2.5 -2.4*(-5)=12 -7.2-7.2=-14.4 8.4÷(-0.04)=-210 1-0.6+0.4=0.8 1.8+1.2*0.6=2.52 (1.5+0.25)*4=7 0.3*0.8÷0.3*0.8=0.64 0.38÷4.3≈0.09

陈庞征21827.2 - 0.4x=4.8 -
都浅良17765749674 ______ 7.2-0.4x=4.80.4x=7.2-4.80.4x=2.4 x=2.4÷0.4 x=6

陈庞征2182(7.2—0.4)x25怎么做 -
都浅良17765749674 ______ (7.2-0.4)*25 =6.8*25 =25*4*1.7 =100*1.7 =170

陈庞征218230十3(x十2)=37.2 -
都浅良17765749674 ______ 30+3(x+2)=37.23(x+2)=37.2-303(x+2)=7.2 x+2=7.2÷3 x=2.4-2 x=0.4

陈庞征2182分别用电源等效变换法和叠加定理,求电路中的电流I和电压U. -
都浅良17765749674 ______ 解:一、电源变换: 12V电压源串联6Ω电阻,等效为12/6=2(A)电流源、并联6Ω电阻; 2A电流源并联1A电流源,等效为3A电流源; 3A电流源并联6Ω电阻,等效为3*6=18V电压源、串联6Ω电阻. 所以:U=18*4/(4+6)=7.2(V). I=(12-7.2)/6=...

陈庞征21827·2乘0·2加2·4乘1·4用简便方法怎样算 -
都浅良17765749674 ______ 7.2*0.2+2.4*1.4 =2.4*3*0.2+2.4*1.4 =2.4*0.6+2.4*1.4 =2.4*(0.6+1.4) =2.4*2 =4.8

陈庞征21827.2*0.4 2.8*0.4 - 1=?用简便运算 -
都浅良17765749674 ______ 7.2x0.4+2.8x0.4-1=(7.2+2.8)x0.4-1=10x0.4-1=4-1=3

陈庞征2182 解方程或比例. 20%x - 0.4=7.2 = 3:8=x:2.4. -
都浅良17765749674 ______[答案] (1)20%x-0.4=7.2, 20%x-0.4+0.4=7.2+0.4, 20%x=7.6, 20%x÷20%=7.6÷20%, x=38;(2)1.8/x=0.3/4, 0.3x=1.8*4, 0.3x÷0.3=7.2÷0.3, x=24;(3)3:8=x:2.4, 8x=3*2.4, 8x÷8=7.2÷8, x=0.9.

陈庞征21827.2 - 6.2x0.4简便运算怎么做? -
都浅良17765749674 ______ 7.2-6.2x0.4=7.2-(6+0.2)*0.4=7.2-2.4-0.08=7.2-2.48=4.72