Question

3X十12=7X十3？

Answer 1

这个简单，你可以把算式变成7x-3x＝12-3
那么4x＝9
x＝9/4=2.25

Answer 2

3x+12=7x+3
7x-3x=12-3
4x=9
x=9÷4
x=2.25

Answer 3

移相得7×-3×=12-3
得。 4×=9
×=9/4

Answer 4

1 + 3 × (1 / 6) + 5 × (1 / 12) + 7 × (1 / 20) + 9 × (1 / 30) + 11 × (1 / 42) = 1 + 1 / 2 + 5 / 12 + 7 / 20 + 3 / 10 + 11 / 42 = 1 + 1 / 2 + (2 + 3) / 12 + (2 + 5) / 20 + (5 - 2) / 10 + (14 - 3) / 42 = 1 + 1 / 2 + 1 / 2 + 1 / 6 + 1 / 6 + 1 / 6 + 1 / 4 + 1 / 10 + 1 / 4 + 1 / 4 + 1 / 2 - 1 / 5 + 1 / 3 - 1 / 14 = 1 + 1 + 1 + 1 / 2 + 1 / 2 + 1 / 2 + 1 / 2 + 1 / 6 + 1 / 6 + 1 / 4 + 1 / 10 + 1 / 4 + 1 / 2 - 1 / 5 + 1 / 3 - 1 / 14 = 1 + 1 + 1 + 1 / 2 + 1 / 2 + 1 + 1 / 2 + 1 / 2+ (1 / 4 + 1 / 4) - (1 / 5 - 1 / 10) - 1 / 14 = 3 - (1 / 10 + 1 / 14) = 3 - 6 / 35 = (2 + 29 / 35)

Answer 5

1+3 × (1/6)+5 × (1/12)+7 × (1/20)+9 × (1/30)+11 × (1/42)=1+1/2+5/12+7/20+3/10+11/42=1+1/2+(2+3)/12+(2+5)/20+(5-2)/10+(14-3)/42=1+1/2+1/6+1/4+1/10+1/4+1/2-1/5+1/3-1/14=1+(1/2+1/2)+(1/6+1/3)+(1/4+1/4)-(1/5-1/10)-1/14=3-(1/10+1/14)=3-6/35=(2+29/35)