1. My mother is fond of going jogging in the morning.

2. My sister find it difficult for her to lift weight.

3. We collected plastic bottles and sent them to the factory.

1. My mother is fond of going jogging in the morning.

2. My sister find it difficult for her to lift weight.

3. We collected plastic bottles and sent them to the factory.

Xét tam giác AMB và tam giác AMD, ta có:

c: AB = AD (gt)

g: góc BAM = góc DAM (gt)

c: AM chung

=> Tam giác AMB = Tam giác AMD (c.g.c)

=> góc ABM = góc ADM (2 góc tương ứng)

BM = MD (2 cạnh tương ứng)

Có góc ABM + góc MBH = 180 độ (kề bù)

góc ADM + góc MDC = 180 độ (kề bù)

=> góc MBH = góc MDC

Xét tam giác MBH và tam giác MDC, ta có:

g: góc MBH = góc MDC (cmt)

c: BM = MD (cmt)

g: góc BMH = góc DMC (đối đỉnh)

=> tam giác MBH = tam giác MDC (g.c.g)

=> BH = DC (2 cạnh tương ứng)

Mà AB = AD (gt)

=> AH = AC

=> tam giác AHC cân tại A (đpcm)

a) Ví dụ:

- Người đàn ông đẩy chiếc ô tô chết máy (người đàn ông tác dụng lực đẩy lên chiếc ô tô chết máy)

- Cậu bé kéo chiếc xe cút kít (cậu bé tác dụng lực kéo lên chiếc xe cút kít)

b)

a) Ví dụ:

- Người đàn ông đẩy chiếc ô tô chết máy (người đàn ông tác dụng lực đẩy lên chiếc ô tô chết máy)

- Cậu bé kéo chiếc xe cút kít (cậu bé tác dụng lực kéo lên chiếc xe cút kít)

b)

Question 1: Robots can work as guards in important places.

Question 2: Hanoi is famous for its delicious street food.

Question 3: What type of house will you live in in the future?

Question 4: Pack your lunch in a lunchbox instead of packing it in a plastic bag.

Question 1: Robots can work as guards in important places.

Question 2: Hanoi is famous for its delicious street food.

Question 3: What type of house will you live in in the future?

Question 4: Pack your lunch in a lunchbox instead of packing it in a plastic bag.

a) \(\dfrac{-5}{9}\) + \(\dfrac{8}{15}\) + \(\dfrac{-2}{11}\) + \(\dfrac{4}{-9}\) + \(\dfrac{7}{15}\)

= \(\dfrac{-5}{9}\) + \(\dfrac{8}{15}\) + \(\dfrac{-2}{11}\) + \(\dfrac{-4}{9}\) + \(\dfrac{7}{15}\)

= \(\left(\dfrac{-5}{9}+\dfrac{-4}{9}\right)\) + \(\left(\dfrac{8}{15}+\dfrac{7}{15}\right)\) + \(\dfrac{-2}{11}\)

= -1 + 1 + \(\dfrac{-2}{11}\)

= 0 + \(\dfrac{-2}{11}\)

= \(\dfrac{-2}{11}\)

b) \(\left(\dfrac{7}{2}.\dfrac{5}{6}\right)\) + (\(\dfrac{7}{6}.\dfrac{7}{2}\))

= \(\dfrac{7}{2}.\dfrac{5}{6}\) + \(\dfrac{7}{6}.\dfrac{7}{2}\)

=7

Ta thấy: \(\dfrac{5}{-12}\) = \(\dfrac{-5}{12}\)

Vì BCNN (8, 12) = 24 nên ta có:

\(\dfrac{-3}{8}\) = \(\dfrac{-3.3}{8.3}\) = \(\dfrac{-9}{24}\)

\(\dfrac{-5}{12}\) = \(\dfrac{-5.2}{12.2}\) = \(\dfrac{-10}{24}\)

Mà -9 > -10 nên \(\dfrac{-9}{24}\) > \(\dfrac{-10}{24}\). Vậy \(\dfrac{-3}{8}\) > \(\dfrac{5}{-12}\)

b) Ta có:

\(\dfrac{3131}{5252}\) = \(\dfrac{3131:101}{5252:101}\) = \(\dfrac{31}{52}\)

Mà \(\dfrac{31}{52}\) = \(\dfrac{31}{52}\) nên \(\dfrac{3131}{5252}\) = \(\dfrac{31}{52}\)