50) \(\sqrt{98-16\sqrt{3}}=4\sqrt{6}-\sqrt{2}\)

51) \(\sqrt{2-\sqrt{3}}=\dfrac{\sqrt{4-2\sqrt{3}}}{\sqrt{2}}=\dfrac{\sqrt{3}-1}{\sqrt{2}}=\dfrac{\sqrt{6}-\sqrt{2}}{2}\)

52) \(\sqrt{4+\sqrt{15}}=\dfrac{\sqrt{8+2\sqrt{15}}}{\sqrt{2}}=\dfrac{\sqrt{5}+\sqrt{3}}{\sqrt{2}}=\dfrac{\sqrt{10}+\sqrt{6}}{2}\)

53) \(\sqrt{5-\sqrt{21}}=\dfrac{\sqrt{10-2\sqrt{21}}}{\sqrt{2}}=\dfrac{\sqrt{14}-\sqrt{6}}{2}\)

54) \(\sqrt{6-\sqrt{35}}=\dfrac{\sqrt{12-2\sqrt{35}}}{\sqrt{2}}=\dfrac{\sqrt{14}-\sqrt{10}}{2}\)

55) \(\sqrt{2+\sqrt{3}}=\dfrac{\sqrt{4+2\sqrt{3}}}{\sqrt{2}}=\dfrac{\sqrt{6}+\sqrt{2}}{2}\)

56) \(\sqrt{4-\sqrt{15}}=\dfrac{\sqrt{8-2\sqrt{15}}}{\sqrt{2}}=\dfrac{\sqrt{10}-\sqrt{6}}{2}\)

Can bac 8

số số hạng có trong biểu thức trên là:

(58 - 40 ) : 1 + 1 = 19

=>( 40 - 41 ) + ( 42 - 43 ) + ... + ( 56 - 57 ) + 58

=> (-1) x  [( 19 - 1 ) : 2 ] + 58

=> (-1) x 9 + 58

=> (-9) + 58
=> 49
HT~~~

Đú đởn ăn chơi học hành sa sút đến nỗi có bài toán đơn giản như zậy mà cũng phải hỏi !

40-41+42-43+44-45+46-47+48-49+50-51+52-53+54-55+56-57+58=

=40+(42-41)+(44-43)+(46-45)+(48-47)+(50-49)+(52-51)+(54-53)+(56-55)+(58-57)=49

chơi ff ko xin id

ta có: 2005 + 53-54-55+56-57-58-59+60+61-62-63+64+65-66-67+68+69

      = 2005+(53-54-55+56)+(57-58-59+60)+(61-62-63+64)+(65-66-67+68)+69

      = 2005+0+0+0+0+69

      = 2005+69

      = 2074

h

các phép tính trong ngoặc đều bằng 0 

suy ra chỉ còn 2005 +69 = 2074 
 

mày bị điên

300

300

= 300 

51. mysteries / seem / beyond / understanding.

those mysteries seem to be beyond understanding.

52. Peter / regret / not attend / lecture / last week.

peter regret not attending the lecture last week

53. time / train / leave / passengers / board.

By the time the train left, all the passengers had been on board.

54. we / upset / because of / failure.

we are upset because of our failure

55. policeman / talk / man / car / damage / accident.

The policeman is talking to the man whose car was dameged in the accident

56. I / spare time / read.

I spend my spare time reading books

57. despite / enthusiasm / he / not succeed.

despite his enthusiam, he didn't succeed

58. more / we / travel / learn.

the more we travel, the more we learn

59. mathematics / play / part / lives.

mathematics play an important part in our lives

60. if / Peter / money / lend / you.

.51. mysteries / seem / beyond / understanding.

There are many mysteries that seem to be beyond our understanding.

52. Peter / regret / not attend / lecture / last week.

Peter regretted not attending the lecture last week.

53. time / train / leave / passengers / board.

54. we / upset / because of / failure.

We were upset because of our fairlure.

55. policeman / talk / man / car / damage / accident.

56. I / spare time / read.

I often spend my spare time reading books.

57. despite / enthusiasm / he / not succeed.

Despite his enthusiasm, he did not succeed.

58. more / we / travel / learn.

The more we travel, the more we learn.

59. mathematics / play / part / lives.

Mathematics plays an important part in our lives.

60. if / Peter / money / lend / you.

Choose the best answer to complete the text.

You can't see our house (51)______ here because it is (52)______ the church. When you walk up Prince Street, it is (53)______ the left, next (54)______ the Black Cat Café.

My room is upstairs (55)______ the right. I have a desk (56)______ front (57)______the window. And I like looking out because our house is (58)______ the park. My desk is (59)______ the bed (60)______ the wardrobe.

51. A. from B. behind C. on D. in

52. A. in B. behind C. on D. between

53. A. on B. at C. in D. under

54. A. in B. at C. on D. to

55. A. in B. behind C. on D. next

56. A. on B. at C. in D. next

57. A. about B. of C. on D. with

58. A. near B. on C. next D. from

59. A. on B. in C. between D. at

60. A. on B. and C. in D. behind

51.a

52.b

53.a

54.d

55.c

56.c

57.b

58.a

59.c

60.b