1024x7.8要怎么简便

0oShmily2o0,59×7/58＋57×5/58＝（58＋1）×7/58＋（58－1）×5/58＝58×7/58＋1×7/58＋58×5/58－1×5/58＝7＋7/58＋5－5/58＝12＋2

276x7分之2÷27.6=276÷27.6×7分之2=10×7分之2=7分之20

先7.5除0.75,再乘26再问：我会，谢谢！

1.wu2.＝4.2×4.2＋4.2×5.8＝4.2×（4.2＋5.8）＝4.2×10＝423.＝1.25×8＋1.25×0.8＋1.25×0.8＝10＋1＋1＝12

3.7x2.5+0.3x2.5=（3.7+0.3）X2.5=4X2.5=100.125x（8+0.8）=0.125X8+0.125X0.8=1+0.1=1.11.6x7.8x1.25=7.8X2X0.

1/1x3+1/3x5+1/5x7+…+1/2009x2011=1/2X【（1-1/3）+（1/3-1/5）+（1/5-1/7）+...+（1/2009-1/2011）=1/2x(1-1/2011)=

7.3*2.7+3.7*7.2=（7.2+0.1）*2.7+（2.7+1）*7.2=7.2*2.7+0.27+2.7*7.2+7.2=19.44+0.27+19.44+7.2=19.44*2+0.27

(-3.85)x(-13)+(-13)x(-6.15)+0.79x7/15+8/15x0.79=(-13)(-3.85-6.15)+0.79x(7/15+8/15)=130+0.79=130.7999

7^4-3x7^2-8x7^3=7^2x(7^2-3-8x7)=7^2x(49-3-56)=49x(-10)=-490(x+y)^2-2(x^2-y^2)+(x-y)^2=(x+y)^2-2(x+y)

（0.8+0.8）×7.5×1.25=0.8×7.5+1.25×0.8

11.72-7.85-1.72=10-7.85=2.1513.8*7.6-7.6*8.8=(13.8-8.8)*7.6=5*7.6=38(0.19*(5.4+2.6))*12.5=0.19*8*12.

=7x7+93x7=7x(7+93)=7x100=700再答：帮个忙

152又2分之1x3分之2+51又4分之1x5分之4+50又6分之1x7分之6=105/2*2/3+205/4*4/5+301/6*6/7=105/3+205/5+301/7=35+41+43=119

 再问：第一题中间那个黑黑的是x号吗再答：对

0.589×76+25×0.589-1×0.589=0.589×（76+25-1）=0.589×100=58.9再答：欢迎加入:http://zhidao.baidu.com/team/view/%E

(4.4x7.5x4.8)除以（1.5x2.5x2.4）=(4.4x2.5x3x2.4x2)除以（1.5x2.5x2.4）=(4.4x3x2)除以1.5=(4.4x2x2x1.5)除以1.5=4.4x

(1)0.64x9.9=0.64x(10-0.1)=0.64x10-0.64x0.1=6.4-0.064=6.336(2)3.14x99+3.14=3.14x(99+1)=3.14x100=314(3

设马=x,年=y,即(x+y)*7=x*10+y即是2y=x因为x,y都是整数,且不大于9所以答案有4种x=2,y=1x=4,y=2x=6,y=3x=8,y=4

354x7+360+355+347=354x7+354+6+354+1+354-7=354x7+354x3=354x(7+3)=3540

1.159²+1.159×7.682+3.841²=1.159²+2×1.159×3.841+3.841²=(1.159+3.841)²=5²