0.86x1.7竖式计算-搜答案-智慧作业帮

答案：C.1/25原式=1/5x1/5=1/25

3.6x1.25十0.32/0.4=0.45x8x1.25+16/20=9/20x1+16/20=25/20=5/4

9.6x(1.4+4.5-1.8+4.9+1)=96

(38+1/36)x1/37=[(37+1)+1/(37-1)]*/37=[(37+1)(37-1)+1]/36*1/37=(37^2-1+1)/36*1/37=37^2/36*1/3737/36

1x1/2+1/2x1/3+1/3x1/4+1/4x1/5+1/5x1/6+1/6x1/7=1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6+1/9-1/7=1-1/7=6/

行列式展开=x1^3+x2^3+x3^3-3x1x2x3而x1^3+x2^3+x3^3-3x1x2x3=（x1+x2+x3)(x1^2+x2^2+x3^2-x1x2-x2x3-x3x1)(展开右边即得

8.8x1.25=(8+0.8)x1.25=8x1.25+0.8x1.25=10+1=11

12.56-5.1×1.8=12.56-(5+0.1)×1.8=12.56-9-0.18=3.56-0.18=3.38

35.55x1.4+(25.2-24.57)=49.77-24.57+25.2=25.2+25.2=50.48/15÷【8/3-（7/4+5/6）】=8/15÷【8/3-31/12】=8/15÷1/1

解58.3x1.6+1.6x41.7=1.6×(58.3+41.7)=1.6×100=160

1.1x1.1x1.1-1.1x1.1-0.1=1.1×1.1×（1.1-1）=1.1×1.1×0.1-0.1=0.121-0.1=0.021

此题运用的是韦达定理的推广.在2次方程情形,韦达定理有一个结论是两根之和等于（-b/a）,推广到3次方程有三根之和：x1+x2+x3=-b/a（其中a为最高次项系数,b为次高项系数,依此类推,初等代数

（0.8+0.8）×7.5×1.25=0.8×7.5+1.25×0.8

7.86×1.5＝11.7962.98×2.1＝132.258望采纳

41.2x8.1+11x1.25+53.7x1.9=41.2x8.1+11x1.25+(41.2x1.9+12.5x1.9)=41.2x(8.1+1.9)+1.25x(11+19)=412+37.5=

您好：35.55x1.4+(25.2-24.57)=49.77-24.57+25.2=25.2+25.2=50.48/15÷【8/3-（7/4+5/6）】=8/15÷(32/12-21/12-10/1

4.9x(1+0.02)=4.9+0.049*2=4.998

（x1-x2）+（2/x1-2/x2）=（X1－X2）＋［（2X2－2X1）÷X1X2］＝（X1－X2）＋［－2（X1－X2）÷X1X2］＝（X1－X2）（1－2÷X1X2）再问：请问为什么还要再÷x