Ta có : x=3 ; y = 2 và z = 5
Hãy tính biểu thức sau :
a. 2z2+1
b. z.x+y.3-7
Nhớ kb vs mik nhé mu a aaaa
nhớ kb nha nhớ nha ko nhớ là giận đó
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Staying safe on foot and bike
Look out for yourself and your friends when out (1)________ foot and bike. Choose the (2) ________ routes you can quieter, slower roads, with pavements if you’re walking or (3) ________ if you’re going by bike.
It’s easy to get distracted by your phone or by friends, but you need to be (4)________ to traffic. Put your phone away and take your earphones (5)________ when crossing the road. Don’t trust that drivers (6)_______ spot you and be able to stop in time – many drivers go too fast and don’t (7) ________ enough attention, (8)________ anything you can do to protect yourself is a good thing.
1. a. on b. in c. by d. with
2. a. safe b. safer c. safest d. safely
3. a. zebra crossings b. cycle paths c. footpaths d. bumpy roads
4. a. risky b. warning c. serious d. alert
5. a. off b. over c. out d. down
6. a. must b. will c. could d. should
7. a. pay b. make c. turn d. take
8. a. but b. so c. though d. because
Look out for yourself and your friends when out (1) A. on foot and bike. Choose the (2) C. safest routes you can quieter, slower roads, with pavements if you’re walking or (3) B. cycle paths if you’re going by bike.
It’s easy to get distracted by your phone or by friends, but you need to be (4) D. alert to traffic. Put your phone away and take your earphones (5) C. out when crossing the road. Don’t trust that drivers (6) B. will spot you and be able to stop in time – many drivers go too fast and don’t (7) A. pay enough attention, (8) B. so anything you can do to protect yourself is a good thing
1,
Áp dụng định lý Py-ta-go vào tam giác AHC vuông tại H ta đc:
\(AH^2+HC^2=AC^2\)
\(\Rightarrow4^2+HC^2=5^2\)
\(\Rightarrow HC^2=9\)
\(\Rightarrow HC=3\left(cm\right)\)
Vì tam giác ABC cân tại A có đường cao AH
=> AH là đường trung tuyến của tam giác ABC
=> H là trưng điểm của BC
=> BC=2HC=2.3=6(cm)
Chu vi tam giác ABC là
AB+BC+AC=5+5+6=16(cm)
2,
Vì tam giác DFE cân tại F có đường cao FM
=> FM là đường trung tuyến của tam giác DFE
=> M là trung điểm của DE
=> \(ME=\frac{1}{2}DE=\frac{1}{2}\cdot8=4\left(cm\right)\)
Áp dụng định lý Py-ta-go vào tam giác FME vuông tại M ta đc
\(FM^2+ME^2=FE^2\)
\(\Rightarrow FM^2+4^2=5^2\)
\(\Rightarrow FM^2=9\)
\(\Rightarrow FM=3\left(cm\right)\)
Diện tích tam giác DFE là:
\(S_{DFE}=\frac{8\cdot3}{2}=12\left(cm^2\right)\)
Bài 1:
Xét \(\Delta AHC\)vuông tại H
\(\Rightarrow AH^2+HC^2=AC^2\)\(\Rightarrow HC^2=AC^2-AH^2=5^2-4^2=9\)
\(\Rightarrow HC=3\)(cm)
Xét \(\Delta ABC\)cân tại A có AH là đường cao
\(\Rightarrow H\)là trung điểm của BC \(\Rightarrow BC=2HC=2.3=6\)(cm)
\(\Rightarrow\)Chu vi \(\Delta ABC\)\(=AB+AC+BC=5+5+6=16\)(cm)
Vậy chu vi \(\Delta ABC\)là 16cm
Bài 12:
Xét \(\Delta DFE\)cân tại F có FM là đường cao
\(\Rightarrow\)M là trung điểm DE \(\Rightarrow ME=\frac{1}{2}DE=\frac{1}{2}.8=4\)(cm)
Xét \(\Delta EMF\)vuông tại M \(\Rightarrow ME^2+MF^2=EF^2\)
\(\Rightarrow MF^2=EF^2-ME^2=5^2-4^2=9\)
\(\Rightarrow MF=3\)(cm)
\(\Rightarrow S_{FDE}=\frac{1}{2}.MF.DE=\frac{1}{2}.3.8=12\left(cm^2\right)\)
Vậy \(S_{FDE}=12cm^2\)
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1. Although I didn't find the film at all frightening.
2. Although most cris agreed that the film was her best ever.
3. Despite being a well-reviewed hit.
4. Although Ben Stiller was the star of this movie.
5. Despite those poor reviews.
6. Despite the fact that they split up over 40 years ago.
7. Although Meryl Streep is more well known for her many Oscar-worthy performances.
8. Despite knowing that it is not true.
1. Although I didn't find the film at all frightening
2. Although most cris agreed that the film was her best ever
3. Despite being a well-reviewed hit
4. Although Ben Stiller was the star of this movie
5. Despite those poor reviews
6. Despite the fact that they split up over 40 years ago
7. Although Meryl Streep is more well known for her many Oscar-worthy performances
8. Despite knowing that it is not true
1
a. y=48/x
b. y=16/3
c. x=-12
2
a. x=-60/y
b. y=-10, 5
c. x= 30, -2