Câu 1: C

Câu 2: B

Câu 3: A

câu 1: 
UCLN(15;19)=1

mink kiểm tra rồi , nhưng tụi mink khác trường mà làm sao các thầy cô giáo cho đề giống nhau được

Lớp mấy vậy bn

lớp 6 nha các bạn 

nhưng khác trưởng cũng được cho mk xin nha

1Yes, i have. 2 I do exercises everyday. 3 I’ll help them to find a new house or give them to someone can do that 

72. have known

73. is coming 

74. flows

75. was listening 

76. did...see

77. worked

78. promise

79. was drinking

80. lost

81. has worked

82. was sitting

83. won't go

84. went - haven't speak

85. doesn't rain

86. leaved

87. was sleeping

88. don't eat

89. was speaking

90. did...smoke

91. has been

92. Have...seen

93. were visiting 

94. arrived

95. Have...been - went

96. give - will sell

97. was making

98. hasn't had

99. returns 

100. met

101. doesn't rain - left

103. took

104. has

105. was climbing

106. have lived

107. am going to watch

108. will lend

109. would have

110. am buying

111. haven't begun

112. arrived - had - went

113. Did...wash

114. is raining - started - has been raining

115. reading - come

Chúc bạn hoc tốt!

ĐKXĐ: \(x\notin\left\{-7;3;-3\right\}\)

a) Ta có: \(B=\left(\dfrac{x^2+1}{x^2-9}-\dfrac{x}{x+3}+\dfrac{5}{x-3}\right):\left(\dfrac{2x+10}{x+3}-1\right)\)

\(=\left(\dfrac{x^2+1}{\left(x-3\right)\left(x+3\right)}-\dfrac{x\left(x-3\right)}{\left(x+3\right)\left(x-3\right)}+\dfrac{5\left(x+3\right)}{\left(x-3\right)\left(x+3\right)}\right):\left(\dfrac{2x+10}{x+3}-\dfrac{x+3}{x+3}\right)\)

\(=\dfrac{x^2+1-x^2+3x+5x+15}{\left(x-3\right)\left(x+3\right)}:\dfrac{2x+10-x-3}{x+3}\)

\(=\dfrac{8x+16}{\left(x-3\right)\left(x+3\right)}\cdot\dfrac{x+3}{x+7}\)

\(=\dfrac{8x+16}{\left(x-3\right)\left(x+7\right)}\)

b) Ta có: |x-1|=2

\(\Leftrightarrow\left[{}\begin{matrix}x-1=2\\x-1=-2\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=3\left(loại\right)\\x=-1\left(nhận\right)\end{matrix}\right.\)

Thay x=-1 vào biểu thức \(B=\dfrac{8x+16}{\left(x-3\right)\left(x+7\right)}\), ta được:

\(B=\dfrac{8\cdot\left(-1\right)+16}{\left(-1-3\right)\left(-1+7\right)}=\dfrac{-8+16}{-4\cdot6}=\dfrac{8}{-24}=\dfrac{-1}{3}\)

Vậy: Khi x=-1 thì \(B=\dfrac{-1}{3}\)

c) Để \(B=\dfrac{x+5}{6}\) thì \(=\dfrac{8x+16}{\left(x-3\right)\left(x+7\right)}=\dfrac{x+5}{6}\)

\(\Leftrightarrow6\left(8x+16\right)=\left(x+5\right)\left(x-3\right)\left(x+7\right)\)

\(\Leftrightarrow48x+96=\left(x^2-3x+5x-15\right)\left(x+7\right)\)

\(\Leftrightarrow\left(x^2+2x-15\right)\left(x+7\right)=48x+96\)

\(\Leftrightarrow x^3+7x^2+2x^2+14x-15x-105-48x-96=0\)

\(\Leftrightarrow x^3+9x^2-49x-201=0\)

\(\Leftrightarrow x^3+3x^2+6x^2+18x-67x-201=0\)

\(\Leftrightarrow x^2\left(x+3\right)+6x\left(x+3\right)-67\left(x+3\right)=0\)

\(\Leftrightarrow\left(x+3\right)\left(x^2+6x-67\right)=0\)

\(\Leftrightarrow\left(x+3\right)\left(x^2+6x+9-76\right)=0\)

\(\Leftrightarrow\left(x+3\right)\left[\left(x+3\right)^2-76\right]=0\)

\(\Leftrightarrow\left(x+3\right)\left(x+3-2\sqrt{19}\right)\left(x+3+2\sqrt{19}\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x+3=0\\x+3-2\sqrt{19}=0\\x+3+2\sqrt{19}=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=-3\left(loại\right)\\x=2\sqrt{19}-3\left(nhận\right)\\x=-2\sqrt{19}-3\left(nhận\right)\end{matrix}\right.\)

Vậy: Để \(B=\dfrac{x+5}{6}\) thì \(x\in\left\{2\sqrt{19}-3;-2\sqrt{19}-3\right\}\)

a: \(=\left(\dfrac{10}{3}+\dfrac{5}{2}\right):\left(\dfrac{19}{6}-\dfrac{21}{5}\right)-\dfrac{11}{31}\)

\(=\dfrac{35}{6}:\dfrac{95-126}{30}-\dfrac{11}{31}\)

\(=\dfrac{35}{6}\cdot\dfrac{30}{-31}-\dfrac{11}{31}\)

\(=\dfrac{-35\cdot5}{31}-\dfrac{11}{31}=\dfrac{-186}{31}=-6\)

b: \(=\left(-8\right)\cdot\dfrac{1}{2}:\left(\dfrac{9}{4}-\dfrac{7}{6}\right)=-4:\dfrac{27-14}{12}=\dfrac{-4\cdot12}{13}=\dfrac{-48}{13}\)

phép tính đầu kết quả là -6

phếp tính thứ 2 kết quả là-48/13