a) x * 2 + x * 3 = 60

x * ( 2 + 3 ) = 60

x = 60 : 5

x = 12

b) x * 15 - x * 9 = 78

x * ( 15 - 9 ) = 78

x = 78 : 6

x = 13

X x 9 + X x 2 - X x 3 - X - 20 = 78

X x ( 9 + 2 - 3 - 1 ) - 20         = 78

               X x 7                    = 78 + 20

               X x 7                    = 98

                   X                     = 98 : 7

                   X                     = 14

Ai k mình mình k lại cho 3 k

    x= .. chờ tí

nhanh lên

3⁷⁸ x 243⁵² = 3⁷⁸ x ( 3⁵ )⁵² = 3⁷⁸ x 3²⁶⁰ = 3³³⁸

9¹⁰¹ x 27⁷⁸ = ( 3² )¹⁰¹ x ( 3³ )⁷⁸ = 3²⁰² x 3²³⁴ = 3⁴³⁶

Vì 338 < 436 

=> 3³³⁸ < 3⁴³⁶

=> 3⁷⁸ x 243⁵² < 9¹⁰¹ x 27⁷⁸

Ta có: 

\(3^{78}\times243^{52}=3^{78}\times\left(3^5\right)^{52}=3^{78}\times3^{260}=3^{338}\)

\(9^{101}\times27^{78}=\left(3^2\right)^{101}\times\left(3^3\right)^{78}=3^{202}\times3^{234}=3^{436}\)

Vì \(3^{338}< 3^{436}\)

\(\Rightarrow3^{338}< 3^{436}\)

\(\Rightarrow3^{78}\times243^{52}< 9^{101}\times27^{78}\left(đpcm\right)\)

`@` `\text {Ans}`

`\downarrow`

`2023 \times 14 + 2023 \times 83+97`

`= 2023 \times (14+83) + 97`

`= 2023 \times 97 + 97`

`= 196231 +97`

`= 196328`

`78 \times 31+78 \times 24+78 \times 17+78 \times 22 \times 72`

`= 78 \times (31+24+17+22 \times 72)`

`= 78 \times (31+24+17+1584)`

`= 78 \times 1656`

`= 129168`

`371 \times 69+371 \times 14+629 \times 83`

`= 371 \times (69+14) + 629 \times 83`

`= 371 \times 83 + 629 \times 83`

`= 83 \times (371+629)`

`= 83 \times 1000`

`= 83000`

`91 \times 51+49 \times 163-49 \times 72`

`= 91 \times 51 + 49 \times (163-72)`

`= 91 \times 51+49 \times 91`

`= 91 \times (51+49)`

`= 91 \times 100`

`= 9100`

`3 \times 12 \times 17 + 4 \times 9 \times 81 + 2 \times 6 \times 6`

`= 9 \times 4 \times 17 + 4 \times 9 \times 81 + 4 \times 9 \times 2`

`= 9 \times 4 \times (17+81+2)`

`= 36 \times 100` 

`= 3600`

`42 \times 17 + 58 \times 83 \times 42 \times 83 + 42 \times 83 + 17`

`= 17 \times (42+58) + 42 \times 83 \times (58 \times 83 +1)`

`= 17 \times 100 + 3486 \times 4815`

`= 1700 + 16785090`

`= 16786790`

65 * 65 + 78 : 9

= 423366666667

máy tính đâu làm mất à ?

ban hoc phan so chua neu roi thi =12701 phan 3

(3x - 9) - 12 = 78

  3x - 9        = 78 + 12

  3x  - 9            = 90 

   3x                  = 90 + 9

  3x                    = 99

   x                       = 33                

huynh ngoc minh tuan 99 sao lai bang =33 ???????????????????

(3x-9)-12=78

       3x-9=78+12

       3x-9=90

         3x=90+9

         3x=99

          x=99:3

    Vậy x=33

\(9^{x-1}=9\)

\(9^{x-1}=9^1\)

\(x-1=1\)

\(x=1+1\)

\(x=2\)

\(\frac{6x-18}{3}+25\times2=78\)

\(\frac{6\left(x-3\right)}{3}+50=78\)

\(2\left(x-3\right)=78-50\)

\(2x-6=28\)

\(2x=28+6\)

\(2x=34\)

\(x=\frac{34}{2}\)

\(x=17\)

a) \(9^{x-1}=9\)

\(\Rightarrow x-1=1\)

\(\Rightarrow x=2\)

Vậy \(x=2\)

b) \(\left(6x-18\right):3+25.2=78\)

\(\Rightarrow3\left(2x-6\right):3+50=78\)

\(\Rightarrow2x-6=38\)

\(\Rightarrow2x=44\)

\(\Rightarrow x=22\)

Vậy \(x=22\)

Giải:

3^x : 9 - 3 + 78

<=> 3^x : 9 = 81

<=> 3^x = 81/9 = 9

<=> 3^x = 3^2

<=> x = 2

 K/l : x = 2.

   Học tốt !