a. \(R=\dfrac{R1\left(R2+R3\right)}{R1+R2+R3}=\dfrac{6\left(2+4\right)}{6+2+4}=3\Omega\)

b. \(U1=U23=U=IR=2.3=6V\)(R1//R23)

\(I23=I2=I3=U23:R23=6:\left(2+4\right)=1A\left(R2ntR3\right)\)

\(\left\{{}\begin{matrix}U2=I2.R2=1.2=2V\\U3=I3.R3=1.4=4V\end{matrix}\right.\)

1 If there were a library in my neighborhood, I could borrow books

2 If I had much free time, I could come to your party

3 If she were a bird, she could fly anywhere

4 Ì you don't study hard, you will fail the test

5 The castle was haunted so we were so scared

6 Despite the bad weather, the football match went on

7 Before she worked in this company, she had been married

8 Because of the dangerous acid rain, the leaves of many plants are damaged

9 Unless you try your best, the result will not be good

10 Because of the heavy rain, the match was cancelled

11 I haven't been to Bang Kok before

12 I have learnt English for 10 years

13 After having done some exercise, Kathy had a shower

14 The last time we talked to each other was 2 weeks ago

9.B

10.C

11.B

12.A

Làm giúp bài nào ạ?

Bài 2: 

a) Xét ΔABD và ΔACE có 

AB=AC(ΔABC cân tại A)

\(\widehat{BAD}\) chung

AD=AE(gt)

Do đó: ΔABD=ΔACE(c-g-c)

Suy ra: BD=CE(hai cạnh tương ứng)

Câu 4: C

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