Matematică
12345magda12345
2015-11-07 04:33:12
va rog mult ex 5.Dau cornita si va rog cu calcule la fie care
Răspunsuri la întrebare
RăzvanChiscop
2015-11-07 07:56:52

a) [2x-7]=5 2x=5+7 2x=12 x=12:2 x=6 b)2 [2x+5]-15=3 2 [2x+5]=15+3 2 [2x+5]=18 [2x+5]=18:2 [2x+5]=9 2x=9-5 2x=4 x=4:2 x=2

ciprianoduminica
2015-11-07 07:58:07

a) |2x-7|=5 I. 2x-7=5 → 2x=5+7 → 2x=12 → x=12:2=6 II. -(2x-7)=5 → -2x+7=5 → 2x=7-5 → 2x=2 → x=2:2=1 b) I. 2(2x+5)-15=3→ 4x+10-15=3 → 4x=3+15-10 → 4x=8 → x=8:4=2 II. -2(2x+5)-15=3→ -4x-10-15=3→ -4x=3+15+10 → x=28/-4=-7 c) I. 3[2(2x-3)-9]-8=7 → 3(4x-6-9)=7+8 3(4x-6-9)=15 4x-6-9=15:3 4x-6-9=5 4x=5+9+6 4x=20 x=20:4=5 II. 3[-2(2x-3)-9]-8=7 → 3(-4x+6-9)=15 -4x+6-9=5 -4x=5+9-6 -4x=8 x=8/-4=-2 e) I. 2x+11-7=8 2x=8+7-11 2x=4 x=4:2=2 II. -(2x+11)-7=8 -2x-11=15 -2x=15+11 -2x=26 x=26/-2=-13 III. -(2x+11-7)=8 -2x-11+7=8 -2x=8-7+11 -2x=12 x=12/-2=-6 IV. -[-(2x+11)-7]=8 2x+11+7=8 2x+18=8 2x=8-18 2x=-10 x=-10/2=-5 d) I. 3[2(2x+3)+4x-9]+5= 4(x+9)+8x-16 3(4x+6+4x-9)+5=4x+36+8x-16 3(8x-3)+5=12x+20 24x-9+5=12x+20 24x-12x=20-5+9 12x=24 x=24:12=2 II. 3[-2(2x+3)+4x-9]+5= 4(x+9)+8x-16 3(-4x-6+4x-9)+5=12x+20 3(-15)+5=12x+20 -45+5=12x+20 -40=12x+20 12x=-40-20 12x=-60 x=-60/12=-5

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