Mark the letter A, B, C or D on your answer sheet to indicate the correct answer to each of the following questions.

Some days of rest may help to _________ the pressure of work.

A. reduce

B. lower

C. chop

D. crease

Mark the letter A, B, C or D on your answer sheet to indicate the correct answer to each of the following questions.

Let’s ask our teacher how to solve this problem _________ we can’t agree on the answer.

A. Since

B. because of

C. due to

D. owing to

dễ

7 cm2 =700mm2

18 hm2 =180000.m2

4300 dm2 =43m2

48 dm2 32 m2 =4832m2

3010m2 =30dam210m2

160 cm2 =1.dm2 .60cm2

câu b,bn lm tuong tu

câu a,bn cưng minh M nằm giữa A;C

=>AM+MC=AC=>CM=AC-AM

Mlà trung điểm của AB=>AM=BM=>CM=AC-BM

Bnằm giũa M,C=>CM=AC-[CM-CB]=>2CM=AC+CB

=>CM=[AC+CB]:2

a)N=1.2+2.3+3.4+4.5+......+99.100

3N=1.2.3+2.3.3+3.3.4+3.4.5+......+3.99.100

3N=1.2.3+2.3.(4-1)+3.4.(5-2)+...........+99.100.(101-98)

3N=1.2.3+2.3.4-1.2.3+3.4.5-2.3.4+.......+99.100.101-98.99.100

3N=99.100.101=999900

N=333300

b)P=10.11+11.12+12.13+....+29.30

3P=10.11.3+11.12.3+....+29.30.3

3P=10.11.12-9.10.11+11.12.13-10.11.12+.........+29.30.31-28.29.30

3P=29.30.31-9.10.11=25980

P=8660

R=1²+2²+3²+....+100²

R=1.(2-1)+2.(3-1)+.........+100.(101-1)

R=1.2-1+2.3-2+3.4-3+.....+100.101-100

R=(1.2+2.3+3.4+..........+100.101)-(1+2+3+.........+99+100)

\(R=\left(N+100.101\right)-\frac{100.101}{2}\)

R=343400-5050=338350

S=100.1+2.(100-1)+3.(100-2)+......+99.(100-98)+100(100-99)

S=100.1+100.2-1.2+100.3-2.3+.......+99.100-98.99+100.100-99.100

S=100(1+2+...+100)-(1.2+2.3+....+99.100)

S=100.(100.101:2)-N

S=505000-333300=171700