\(5\cdot4^2-18:3^2\)

\(=5\cdot16-18:9\)

\(=80-2\)

\(=78\)

________________

\(6^2:4\cdot3+2\cdot5^3\)

\(=36:12+2\cdot125\)

\(=3+250\)

\(=253\)

_______________

\(80-\left(4\cdot5^2-3\cdot2^3\right)\)

\(=80-\left(4\cdot25-3\cdot8\right)\)

\(=80-\left(100-24\right)\)

\(=80-76\)

\(=4\)

6² : 4 . 3 + 2 . 5³

= 36 : 4 . 3 + 2 . 125

= 9 . 3 + 250

= 27 + 250

= 277

Hai bài còn lại xem của bạn Phong nhé. Bài này Phong giải chưa chính xác nên Thầy giải lại cho em!

a: \(5^6:5^3+2^3:2^2\)

\(=5^3+2\)

=125+2

=127

b: \(3333:3+225:15\)

=1111+15

=1126

c: \(15\cdot2^3+4\cdot3^2-5\cdot7\)

\(=15\cdot8+4\cdot9-35\)

=120+36-35

=121

d: \(5\cdot4^2-18:3^2\)

\(=5\cdot16-18:9\)

=80-2=78

e: \(6^2:4\cdot3+2\cdot5^2\)

\(=36:4\cdot3+2\cdot25\)

=27+50

=77

f: \(80-\left(4\cdot5^2-3\cdot2^3\right)\)

=80-(100-24)

=80-76

=4

Lời giải:

a. 

$=5^{6-3}+2^{3-2}=5^3+2^1=125+2=127$
b.

$=3333:3+225:15=1111+15=1126$

c.

$=15.2^3+4.3^2-5.7=15.8+4.9-35=120+36-35=120+1=121$

d.

$=5.4^2-18:3^2=5.16-18:9=80-2=78$

e.

$=6^2:4.3+2.5^3=36:4.3+2.125$

$=9.3+250=27+250=277$

f.

$=80-(4.25-3.8)=80-(100-24)=80-100+24=-20+24=4$

4,8 x 5,7 + 5,7 x 2,7 = 5,7 x ( 4,8 + 2,7 ) = 5,7 x 7,5 = 42,75

9,3 x 5,4 - 5,4 x 4,3 = 5,4 x ( 9,3 - 4,3 ) = 5,4 x 5 = 27

a,5.7x(4.8 + 2.7)

=5,7x7,5

=?

b, 5,4x(9,3-4,3)

=5,4x5

=?

a, 4,8 x 5,7 + 5,7 x 2,7

= 5,7 x ( 4,8 + 2,7)

= 5,7 x 7,5

= 42,75

b, 9,3 x 5,4 - 5,4 x 4,3

= 5,4 x ( 9,3 - 4,3)

= 5,4 x 5

= 27

Ta có: 1/4 < (1+1)/(4+1) = 2/5

           3/6 < (3+1)/(6+1) = 4/7

                 .......................

           995/998 < (995+1)/(998+1) = 996/999

           997/1000 <(997+1)/(1000+1) =998/1001

123-5.(x+4)=38

5.(x+4)=123-38

5.(x+4)=85

x+4=85:5

x+4=17

x=17-4

x=13

(3.x-2^4).7^3=2.7^4

(3.x-16).343=2.2401

(3.x-16).343=4802

3.x-16=4802:343

3.x-16=14

3.x=14+16

3.x=30

x=30:3

x=10

6^2:4.3+2.5^2

=36:4.3+2.25

=9.3+2.25

=27+50

=77

5.4^2-18:3^2

=5.16-18:9

=80-2

=78

80-(4.5^2-3.2^3)

=80-(4.25-3.8)

=80-(100-24)

=80-76

=4

23.75+25.23+180

=23.(75+25)+180

=23.100+180

=2300+180

=2480

2448:[119-(23-6)]

=2448:(119-17)

=2448:102

=24

(2600+6400)-3.x=1200

9000-3.x=1200

3.x=9000-1200

3.x=7800

x=7800:3

x=2600

[(6.x-72):2-84].28=562

(6.x-72):2-84=562:28

(6.x-72):2-84=281/14

(6.x-72):2=281/14+84

(6.x-72):2=1457/14

6.x-72=1457/14.2

6.x-72=1457/7

6.x=1457/7+72

6.x=1961/7

x=1961/7:6

x=1961/42

14-(1.18x X+3.2):2=6.5

       (18x X+6):2   =14-6.5

       (18x X+6):2   =7.5

        18x X+6       =7.5x2

        18x X+6       =15

        18x X           =15-6

        18x X           = 9

              X           = 9:18

              X           = 0.5

3.2x + 4.3x - 2.7 = 3.9

6x + 12x - 14 = 27

x ( 6 + 12 ) = 27 -14 = 13

18x = 13

=> x = 13 : 18 = \(\frac{13}{18}\)

Chúc bạn học tốt