Mn ơi giúp mik vs !! Mik cảm ơn trc^^
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2:
a: |x-2021|=x-2021
=>x-2021>=0
=>x>=2021
b: 5^x+5^x+2=650
=>5^x+5^x*25=650
=>5^x*26=650
=>5^x=25
=>x=2
c: Áp dụng tính chất của DTSBN, ta được:
\(\dfrac{x-1}{2}=\dfrac{y-2}{3}=\dfrac{2x+3y-2-6}{2\cdot2+3\cdot3}=2\)
=>x-1=4 và y-2=6
=>x=5 và y=8
5:
a: Xét tứ giác ABKC có
M là trung điểm chung của AK và BC
=>ABKC là hình bình hành
=>góc ABK=180 độ-góc CAB=80 độ
b: ABKC là hình bình hành
=>góc ABK=góc ACK
góc DAE=360 độ-góc CAB-góc BAD-góc CAE
=180 độ-góc CAB=góc ACK
Xét ΔABK và ΔDAE có
AB=DA
góc ABK=góc DAE
BK=AE
=>ΔABK=ΔDAE
c. \(\left|\dfrac{8}{4}-\left|x-\dfrac{1}{4}\right|\right|-\dfrac{1}{2}=\dfrac{3}{4}\)
\(\Rightarrow\left[{}\begin{matrix}\left|\dfrac{8}{4}-x+\dfrac{1}{4}\right|-\dfrac{1}{2}=\dfrac{3}{4}\\\left|\dfrac{8}{4}+x-\dfrac{1}{4}\right|-\dfrac{1}{2}=\dfrac{3}{4}\end{matrix}\right.\) \(\Rightarrow\left[{}\begin{matrix}\left|\dfrac{9}{4}-x\right|-\dfrac{1}{2}=\dfrac{3}{4}\\\left|\dfrac{7}{4}+x\right|-\dfrac{1}{2}=\dfrac{3}{4}\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}\left[{}\begin{matrix}\dfrac{9}{4}-x-\dfrac{1}{2}=\dfrac{3}{4}\\x=\dfrac{9}{4}-\dfrac{1}{2}=\dfrac{3}{4}\end{matrix}\right.\\\left[{}\begin{matrix}\dfrac{7}{4}+x-\dfrac{1}{2}=\dfrac{3}{4}\\-\dfrac{7}{4}-x-\dfrac{1}{2}=\dfrac{3}{4}\end{matrix}\right.\end{matrix}\right.\) \(\Rightarrow\left[{}\begin{matrix}\left[{}\begin{matrix}x=1\\x=\dfrac{7}{2}\end{matrix}\right.\\\left[{}\begin{matrix}x=-\dfrac{1}{2}\\x=-3\end{matrix}\right.\end{matrix}\right.\) \(\Rightarrow\left[{}\begin{matrix}x=1\\x=\dfrac{7}{2}\\x=-3\end{matrix}\right.\)
Ở nơi x=9/4-1/2 là x-9/4-1/2 nha
a. -1,5 + 2x = 2,5
<=> 2x = 2,5 + 1,5
<=> 2x = 4
<=> x = 2
b. \(\dfrac{3}{2}\left(x+5\right)-\dfrac{1}{2}=\dfrac{4}{3}\)
<=> \(\dfrac{3}{2}x+\dfrac{15}{2}-\dfrac{1}{2}=\dfrac{4}{3}\)
<=> \(\dfrac{9x}{6}+\dfrac{45}{6}-\dfrac{3}{6}=\dfrac{8}{6}\)
<=> 9x + 45 - 3 = 8
<=> 9x = 8 + 3 - 45
<=> 9x = -34
<=> x = \(\dfrac{-34}{9}\)
C
1 cooking
2 listening
3 reading
4 playing
5 cycling
1 People collect a lot of things such as stamps, milk bottle labels, comic books as well as car toys
2 She is 20 years old
3 She is a hairdresser
4 It is collecting candy shells
5 Her friends and relatives
B
1 F
2 F
3 F
4 F
5 T
Do \(\dfrac{a}{b}=\dfrac{c}{d}\Rightarrow\dfrac{b}{a}=\dfrac{d}{c}\)
\(\Rightarrow1-\dfrac{b}{a}=1-\dfrac{d}{c}\Rightarrow\dfrac{a-b}{a}=\dfrac{c-d}{c}\) (đpcm)
2 Without his sister's help, John couldn't have done his homework
3 Instead of driving to work, I go by bus today
4 Mai doesn't mind giving you a hand
5 They don't know much about English
6 The noise prevented him from sleeping
7 The police have investigated the case for a week
8 We never had an intention of travelling abroad
9 Mary is believed to get the scholatship
10 Instrad of slowing down, he drove faster