这几道数学题我不会啊.帮帮忙.1、 怎样算简便就怎样算3 ×( 23 + 13 )- 12 (712 + 12 - 112 )÷1415 12 × ( 12 + 34 - 16 ) [1 -(14 + 320 )] ÷ 15 2、 解方程 X –27 X = 514 2.5X – 3.2 = 4.8 X ÷ 34 = 1516 411 ÷X = 711 要过程哦.赶快.

问题描述:

这几道数学题我不会啊.帮帮忙.
1、 怎样算简便就怎样算
3 ×( 23 + 13 )- 12 (712 + 12 - 112 )÷1415
12 × ( 12 + 34 - 16 ) [1 -(14 + 320 )] ÷ 15
2、 解方程
X –27 X = 514 2.5X – 3.2 = 4.8
X ÷ 34 = 1516 411 ÷X = 711
要过程哦.赶快.

3×( 23 + 13 )- 12 (712 + 12 - 112 )÷1415
=3×36-12×612÷1415
=108(1-68÷1415)
=-145476/1415
12 × ( 12 + 34 - 16 ) [1 -(14 + 320 )] ÷ 15
=12×30×(-333)÷15
=-7992
X –27 X = 514
-26X=514
X=-257/13
2.5X – 3.2 = 4.8
2.5X=8
X=3.2
X ÷ 34 = 1516
X=173944
411 ÷X = 711
X=411/711=137/237