\(\dfrac{1}{a}+\dfrac{1}{b}=\dfrac{1}{3}\\ =>\dfrac{3a+3b}{3ab}=\dfrac{ab}{3ab}\\ =>3a+3b-ab=0\\ =>a\left(3-b\right)+3b=0\\ =>a\left(3-b\right)-3\left(3-b\right)+9=0\\ =>\left(3-b\right)\left(a-3\right)=-9\\ =>\left(b-3\right)\left(a-3\right)=9=1.9=3.3=\left(-1\right).\left(-9\right)=\left(-3\right).\left(-3\right)\)

Do `0<a<b=>-3<a-3<b-3`

`=>a-3=1;b-3=9=>a=4;b=12`

Vậy `(a;b)=(4;12)`

6 = 2 + 2 + 2;

7 = 3 + 2 + 3;

8 = 3 + 3 + 2

a. 243 : 3 ^ 3 = 243 : 27 = 9 

b. 729 : 3^3 : 9 = 729 : 27 : 9 = 27 : 9 = 3 

c, 1003: ( 2^2 .25^2) = 1003 : ( 4 . 625 ) = 1003 : 2500 = 0,4012 

a) 243 : 27 = 9

b)729:27: 9 = 27:9=3

c)1003 : ( 4.100) = 1003 : 400 = 25072

1. 2 = 1.1 + 2.1

35 = 3x10 + 5x1

24 = 2x10 + 4x1

19 = 1x10 + 9x1

235 = 100 x 2 + 10 x 3 + 1 x5

467 = 100 x 4 + 10 x 6 + 1x 7

356 = 3x100 + 10 x 5 + 1x6

678 = 100 x 6 + 10 x7 + 1 x8

3676 = 1000 x 3 + 100 x 6 + 10 x7+1x6

7663 = 1000 x 7 + 100 x6 + 10 x 6 + 1x3 

...

df

ko

giúp mình với mình đang cần gấp!!

3x.3=243   

= 3x.3=3⁵

= x= 4

 2x.162=1024   

= 2^x . 256  = 1024

= 2^x = 1024 : 256

= 2^x = 4 = 2²

= x = 2

 64.4x=168 

= 4³ . 4^x = 4^{1 6}

= 4^x = 4^{1 6 - 3}

= 4^x = 1 3

= x = 13

  2x=16

= 2^x = 2⁴

= x = 2

ho

mh

24.13 - 12.16

= 12.2.13 - 12.16

=12.26 -12.16

=12.(26-16)

=12.10

=120

   24.13 - 12.16

= 312 - 192 = 120