Lời giải:

$(x-15)-x.13=0$

$x-15-x.13=0$

$(x-x.13)-15=0$

$x(1-13)-15=0$

$x.(-12)-15=0$

$x.(-12)=15$

$x=15:(-12)=\frac{-5}{4}$

170

   m : 3 + 20 * n với m =150 ; n=6 
⇒150 : 3 + 20 . 6
⇒50 + 120
⇒170
 

30+(3+6)=39

30 + (3 + 6) = 39

cảm ơn 

\(=\dfrac{1}{\sqrt{x}+1}-\dfrac{\sqrt{x}}{\sqrt{x}-1}=\dfrac{\sqrt{x}-1-x-\sqrt{x}}{x-1}=\dfrac{-x-1}{x-1}\)

\(\dfrac{1}{\sqrt{x}+1}+\dfrac{\sqrt{x}}{1-\sqrt{x}}\)

\(=\dfrac{1}{\sqrt{x}+1}-\dfrac{\sqrt{x}}{\sqrt{x}-1}\)

\(=\dfrac{\sqrt{x}-1-x-\sqrt{x}}{x-1}=\dfrac{-1-x}{x-1}\)

1.

1G 2F 3E 4H 5A 6D 7B 8C

2. 

1F 2C 3G 4E 5B 6H 7A 8D

2.

1 hurry up

2 ring me up

3 heal

4 fill up

5 seal it up

6 locked him up

7 saved up

8 tidy up

38/D
39/C
40/A

38:D

đáp án là                                                                                                                                                                                                        38D

39c
40a
chúc bạn học tốt

C

C

so?

\(m\left(2m-3\right)-2m\left(m+1\right)\)

\(=2m^2-3m-2m^2-2m=-5m⋮5\Rightarrow dpcm\)

\(m\left(2m-3\right)-2m\left(m+1\right)\)

\(=2m^2-3m-2m^2-2m\)

\(=-5m⋮5\) \(\forall m\in Z\)

Vậy \(m\left(2m-3\right)-2m\left(m+1\right)⋮m\left(\forall m\in Z\right)\)

cảm ơn bạn^^

\(45m+35m+m+19m\)

\(=m\left(45+35+1+19\right)\)

\(=100m\)

\(45m+35m+m+19m=100m\)

=m x (45+35+1+19)
=m x 100
= 100m