c)Ta có: ΔKOE = ΔMAE (cmt)​

=> góc KOE = góc MAE( 2 góc tương ứng)

mà 2 góc ở vị trí slt

=> OK // MA hay OK // MB ( vì A,M,B thẳng hàng )

mà OK = MB (cmt)

=> Tứ giác OBMK là hình bình hành

=> KM // OB (đpcm)

Ko biết lớp 7 học dấu hiệu nhận biết hbh chưa nhể?

Bài 1 : nBa(2+)=0,1.0,5+0,1.0,4=0,09 mol
nHCO₃- = 0,1 mol --> n CO₃(2-)=0,1 mol
-->nCO₃(2-)>nBa(2+)
nBaCO₃ = 0,09 mol
--->mBaCO₃=17,73g

Bài 2: Mg + 2FeCl₃ --> MgCl₂ + 2FeCl₂
Mg + FeCl₂ --> MgCl₂ + Fe
Nếu sau pư Mg dư thì m rắn = mMg dư +mFe = m Mg dư + 56x0.12 = mMg dư + 6.72 > 3.36g
Vậy chất rắn sau pư chỉ có Fe
n = 0.06 mol
nMg = 0.5n FeCl₃ + nFe = 0.5x0.12 + 0.06 = 0.12mol
=> m = 2.88g
 

a.designers

b.examination

c.attend

d.reputation

e.cultural

g.enjoyable

h.exactly

i.reasonable

7.Travel, is a process of continually at its best, conquering disbelief.

1) 1. The students decided to go an excursion because they wanted to relax after work.

2) The Brown are going to the cinema this evening.

3. Did you hear any noise at night?
4. We had to use our neighbor's telephone because ours was out of order.
5. Her father is learning with a German teacher.
6. Rosalie has visited the village several times before.
8. A business trip or official trip is a journey emerged from business necessities.
9. Peter often learns English three periods a week.
10. Neither of the farmhouses has a heater in it.

Kết thúc đẹp chứ nhỉ :

Thay x = 8 ; y = 2 vào ta có :

4x + 2y - 5x = 4.8 + 2.2 - 5.8 = 32 + 4 - 40 = -4

A