\(\left(\frac{2-\sqrt{5}}{2+\sqrt{5}}-\frac{2+\sqrt{5}}{2-\sqrt{5}}\right):20.\)

= \(\left(\frac{\left(2-\sqrt{5}\right)^2-\left(2+\sqrt{5}\right)^2}{\left(2+\sqrt{5}\right)\cdot\left(2-\sqrt{5}\right)}\right):20\)

= \(\left(\frac{4-2\sqrt{5}+5-4-2\sqrt{5}-5}{\left(2+\sqrt{5}\right)\cdot\left(2-\sqrt{5}\right)}\right):20\)

= \(\frac{-4\sqrt{5}}{4-5}:20\)

= \(\frac{-\sqrt{5}}{5}\)

hok tốt =>

B=50x49+53x50

B=50x(49+53)

B=50x102

vậy A<B vì 50x101<50x102

Bg

Ta có: A = 101.50 và B = 50.49 + 53.50

Xét B = 50.49 + 53.50:

=> B = 50.(49 + 53)

=> B = 50.102

Vì 101.50 < 50.102 nên A < B

Vậy A < B

choose the best  answer

1.my hobby is ..............dolls (collect/collecting/collects/collected)

2.he does................everyday.(camping/babminton/gymnass/photos)

3.my younger brother loves..................monopoly with me evrery evening.(riding/talk/playing/walking)

4.they....................that swimming is interesting .(/think/have/make)

5.they ...................shopping for food on sundays.(collect/are doing/will go/go)

1.collecting

2.badminton

3.talk

4.think

5.will go

Ta có :

\(\frac{n^2+2n+1}{n+23}\in Z\Rightarrow n^2+2n+1⋮n+23\)

\(\Rightarrow n^2+23n-\left(21n-1\right)⋮n+23\)

\(\Rightarrow n\left(n+23\right)-\left(21n-1\right)⋮n+23\)

Mà \(n\left(n+23\right)⋮n+23\)

\(\Rightarrow21n-1⋮n+23\)

\(\Rightarrow21n+483-484⋮n+23\)

\(\Rightarrow21\left(n+23\right)-484⋮n+23\)

,Mà \(21\left(n+23\right)⋮n+23\)

\(\Rightarrow484⋮n+23\)

Vậy n lớn nhất \(\Leftrightarrow n+23=484\)

\(\Leftrightarrow n=461\)

\(\sqrt{x^2-8x+16}+\left|x+2\right|=0\)

<=> \(\sqrt{\left(x-4\right)^2}+\left|x+2\right|=0\)

<=> \(\left|x-4\right|+\left|x+2\right|=0\)

<=> \(\left|4-x\right|+\left|x+2\right|=0\)

Ta thấy: \(\left|4-x\right|+\left|x+2\right|\ge\left|4-x+x+2\right|=\left|6\right|=6\)

mà \(\left|4-x\right|+\left|x+2\right|=0\)

=> pt vô nghiệm

(556/31-31/8)-(90/31-4)

3567/248-(90/31-4)

3567/248+34/31

3839/248

Không tính hợp lý được hả bạn ?

aha X_X

trả lời

15+15=30

học tốt

a) 2001 x 757 + 2002 x 233

    = 2001 x 757 + (2001 + 1) x 233

    = 2001 x 757 + 2001 x 233 + 1 x 233

    = 2001 x (757+233) + 233

    = 2001 x 1000 + 233

    = 2001000 + 233

    = 2001233

a) 2001x757+2002x243

=2001 x 757+ (2001+1) x233

=2001 x757+2001x233+1 x233

=2001x(757+233)+233

=2001x1000 +233

=201000+233

=2001233

b)(m:1-m x1):(mx2001+m+1)

=(m-m):(mx2001+m+1)

=0:(mx2001+m+1)

=0

   Học tốt

olm chưa death ak ?

a; - \(\dfrac{1}{3}\).(15\(x-9\)) + \(\dfrac{2}{7}\).(- \(x-34\)) = 1 - \(\dfrac{3}{4}\).(-16\(x+4\))

    - 5\(x\) + 3 - \(\dfrac{2}{7}\)\(x\) - \(\dfrac{68}{7}\) = 1 + 12\(x\) - 3 

    12\(x\) + 5\(x\)  + \(\dfrac{2}{7}x\) =  3 - \(\dfrac{68}{7}\)  - 1 + 3 

    17\(x\) + \(\dfrac{2}{7}x\) =  (3 - 1 + 3) - \(\dfrac{68}{7}\)

    \(\dfrac{121}{7}\)\(x\)    =  5 - \(\dfrac{68}{7}\)

     \(\dfrac{121}{7}\) \(x\)  = -  \(\dfrac{33}{7}\)

           \(x\)  =    - \(\dfrac{33}{7}\): \(\dfrac{121}{7}\)

            \(x\) =  - \(\dfrac{3}{11}\)

Vậy  \(x\) = - \(\dfrac{3}{11}\)