a, Xét Δ ABC, có :

\(BC^2=AB^2+AC^2\) (định lí Py - ta - go)

=> \(BC^2=10^2+8^2\)

=> \(BC^2=164\)

=> \(BC=12,8\left(cm\right)\)

b, Xét Δ ABE và Δ HBE, có :

\(\widehat{ABE}=\widehat{HBE}\) (BE là tia phân giác \(\widehat{ABC}\))

\(\widehat{BAE}=\widehat{BHE}=90^o\)

BE là cạnh chung

=> Δ ABE = Δ HBE (g.c.g)

=> AB = HB

Xét Δ ABH, có : AB = HB (cmt)

=> Δ ABH cân tại B

c,

Gọi O là giao điểm của tia AH và BE

Xét Δ cân ABH, có :

BO là tia phân giác \(\widehat{ABH}\)

=> BO là đường cao

=> \(BO\perp AH\)

=> \(BE\perp AH\)

24 : ( 3x -2 ) = -3

       ( 3x - 2 ) = 24 : -3 

       ( 3x -2 ) = -8

       3x          = -8 + 2

       3x          = -6

         x          = -6 : 3

         x           = -2

3x-2 = 24: (-3)

3x-2 = -8

3x = (-8) +2

3x = -6

x = -6:3

x = -2

c) 24 : (3x - 2) = -3

            3x - 2  = 24 : (-3)
            3x - 2  = -8

            3x      = (-8) + 2

            3x      = -6

              x      = (-6) : 3

              x      = -2

nhìn hơi rối

bn tách ra đc k ặc

a,1/5+4/11+4/5+7/11

=(1/5+4/5)+(4/11+7/11)

=1+1

=2

Chọn B

1367.54+1367.45+1367

=1367.(54+45+1)
=1367.100

=136700

a) 1/5 + 4/11 + 4/5 + 7/11 = (1/5 + 4/5) + (4/11 + 7/11) = 1 + 1 = 2

=> B

b) 1367 x 54 + 1367 x 45 + 1367 = 1367 x (54 + 45 + 1) = 1367 x 100 = 136700

I

2 He didn't used to go to work by car

3 We used to fly kites when we lived in the countryside

4 Because the festival was held on Sunday, a lot of people attended it

5 Despite being tired, she still finished her work

6 Although the story of the film wasn't good, I enjoyed the acting

7 Although the price of electricity is high, he uses it wastefully

8 Despite the fact that she performed well, she didn't receive good comments from critist

9 This is his first role. However, his acting is excellent

10 Even though it was a comedy, almost audience fell asleep

1.How far is it from HN to HP?

2.He didn't use to go to work by car.

3. We used to fly kites when we lived in the countryside

4. Because it was held on Sunday, a lot of people attended it.

5. Despite being tired, she still finished her work

6.Although the story of the film wasn't good, I enjoyed the acting.

7.Although the price of electricity is high, he uses it wasteful.

8. Despit the fact that she performed well,she didn't receive good comments from critics

9.This is his first role. However, his acting is excellent.

10.Even though it was a comedy, audiences fell as sleep.

5: =10-28+30-4=40-32=8

Bài II:

1: Ta có: \(x+\dfrac{3}{5}=\dfrac{1}{2}-\dfrac{3}{10}\)

\(\Leftrightarrow x+\dfrac{3}{5}=\dfrac{1}{5}\)

hay \(x=-\dfrac{2}{5}\)