Đáp án:

1)134-2{156-6.[54-2.(32+6)]}.x=86

134-2.{156-6.[54-2.(9+6)]}.x=86

134-2.{156-6.[54-2.15]}.x=86

134-2.{156-6.[54-30]}.x=86

134-2.{156-6.24}.x=86

134-2.{156-144}.x=86

134-2.12.x=86

2.12.x=134-86

2.12.x=48

12.x=48:2

12.x=24

x=24:12

x=2

2){[5-2x]+14}:3+5.(8-2)-25=10

{[5-2x]+14}:3+5.6-25=10

{[5-2x]+14}:3+30-25=10

{[5-2x]+14}:3+5=10

{[5-2x]+14}:3=10-5

{[5-2x]+14}:3=5

[5-2x]+14=5.3

[5-2x]+14=15

5-2x=15-14

5-2x=1

2x=5-1

2x=4

x=4:2

x=2

3){2.20180.[(x2-4).3]+23.32-102}+6=2.52

{2.1.[(x2-4).3]+8.9-100}+6=2.2

{2.1.[(x2-4).3]+8.9-100}+6=50

2.1.[(x2-4).3]+8.9-100=50-6

2.1.[(x2-4).3]+8.9-100=44

2.1.[(x2-4).3]+72-100=44

2.1.(x2-4).3+72=100+44

2.1.(x2-4).3+72=144

2.(x2-4).3+72=144:1

2.(x2-4).3+72=144

2.(x2-4).3=144-72

2.(x2-4).3=72

(x2-4).3=72:2

(x2-4).3=36

x2-4=36:3

x2-4=12

x2=12+4

x2=16

x=4

Giải thích các bước giải:

1) 134 - 2 { 156 - 6 * [ 54 - 2 * ( 3^2 + 6 )]}*x = 86

=> 134 - 2 { 156 - 6 * [ 54 - 2 * ( 9 + 6 )]} * x = 86

=> 134 - 2 { 156 - 6 * [ 54 - 2 * 15 ] * x = 86

=> 134 - 2 { 156 - 6 * [ 54 - 30 ] * x = 86

=> 134 - 2 { 156 - 6 * 24 } * x = 86

=> 134 - 2 { 156 - 144 } * x = 86

=> 134 - 2 * 12 * x = 86

=> 134 - 24 * x = 86

=> 24x = 134 - 86

=> 24x = 48

=> x = 48 : 24

=> x = 2

___

2) {[ 5 - 2x ] + 14 } : 3 + 5 * ( 8 - 2 ) - 25 = 10

=> {[ 5 - 2x ] + 14 } : 3 + 5 * 6 - 25 = 10

=> {[ 5 - 2x ] + 14 } : 3 + 30 = 10 + 25

=> {[ 5 - 2x ] + 14 } : 3 + 30 = 35

=> {[ 5 - 2x ] + 14 } : 3 = 35 - 30

=> {[ 5 - 2x ] + 14 } : 3 = 5

=> [ 5 - 2x ] + 14 = 5 * 3

=> [ 5 - 2x ] + 14 = 15

=> 5 - 2x = 15 - 14

=> 5 - 2x = 1

=> 2x = 5 - 1

=> 2x = 4

=> x = 4 : 2

=> x = 2

___

3) { 2 * 2018^0 * [( x^2 - 4 ) * 3 ] + 2^3 * 3^2 - 10^2 } + 6 = 2 * 5^2

=> { 2 * [( x^2 - 4 ) * 3 ] + 8 * 9 - 100 } + 6 = 2 * 25

=> { 2 * [( x^2 - 4 ) * 3 ] + 72 - 100 } + 6 = 50

=> 2 * [( x^2 - 4 ) * 3 ] + 72 - 100 = 50 - 6

=> 2 * [( x^2 - 4 ) * 3 ] + 72 - 100 = 44

=> 2 * [( x^2 - 4 ) * 3 ] + 72 = 44 + 100

=> 2 * [( x^2 - 4 ) * 3 ] + 72 = 144

=> 2 * [( x^2 - 4 ) * 3 ] = 144 - 72

=> 2 * [( x^2 - 4 ) * 3 ] = 72

=> ( x^2 - 4 ) * 3 = 72 : 2

=> ( x^2 - 4 ) * 3 = 36

=> x^2 - 4 = 36 : 3

=> x^2 - 4 = 12

=> x^2 = 12 + 4

=> x^2 = 16

=> x^2 = (+-4)^2

=> x = +-4

@HYC