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Câu 1:
\(4\sqrt[4]{\left(a+1\right)\left(b+4\right)\left(c-2\right)\left(d-3\right)}\le a+1+b+4+c-2+d-3=a+b+c+d\)
Dấu = xảy ra khi a = -1; b = -4; c = 2; d= 3
\(\frac{a^2}{b^5}+\frac{1}{a^2b}\ge\frac{2}{b^3}\)\(\Leftrightarrow\)\(\frac{a^2}{b^5}\ge\frac{2}{b^3}-\frac{1}{a^2b}\)
\(\frac{2}{a^3}+\frac{1}{b^3}\ge\frac{3}{a^2b}\)\(\Leftrightarrow\)\(\frac{1}{a^2b}\le\frac{2}{3a^3}+\frac{1}{3b^3}\)
\(\Rightarrow\)\(\Sigma\frac{a^2}{b^5}\ge\Sigma\left(\frac{5}{3b^3}-\frac{2}{3a^3}\right)=\frac{1}{a^3}+\frac{1}{b^3}+\frac{1}{c^3}+\frac{1}{d^3}\)
Làm tạm một câu rồi đi chơi, lát làm cho.
4)
Áp dụng bất đẳng thức Cauchy-Schwarz :
\(VT\ge\frac{\left(1+1+1\right)^2}{a^2+b^2+c^2+2ab+2bc+2ca}=\frac{9}{\left(a+b+c\right)^2}\ge\frac{9}{1}=9\)
Dấu "=" xảy ra \(\Leftrightarrow a=b=c=\frac{1}{3}\)
Tìm từ có trọng âm khác
1/ A. student B. member C. prefer D. teacher
2 A. subject B. hello C. teacher D. thousand
3 A. lesson B. woman C. repair D. father
4 A. above B. sister C. widen D. very
5/ A. corner B. answer C. doctor D. prepare
1. A. looked B. watched C. carried D. stopped
2. A. study B. success C. surprise D. sugar
3. A. unite B. underline C. university D. uniform
4. A. danger B. angry C. language D. passage
5. A. character B. children C. teacher D. change
1. a. am b. is c. are. d. was
2. a. sometimes b. birthday c. always d. usually
3. a. teacher b. doctor c. factory d. worker
4. a. Festival b. June c. March d. August
5. a. sang b. drew c. had d. played
Choose the word whose underlined part pronounced differently from that of the others.
1. A. books B. pencils C. rulers D. bags
2. A. read B. teacher C. eat D. ahead
3. A. tenth B. math C. brother D. theater
4. A. has B. name C. family D. lamp
5. A. does B. watches C. finishes D. brushes
1. A. books B. pencils C. rulers D. bags
2. A. read B. teacher C. eat D. ahead
3. A. tenth B. math C. brother D. theater
4. A. has B. name C. family D. lamp
5. A. does B. watches C. finishes D. brushes
Câu 1: A. computer B. situation C. telephone D. teacher
Câu 2: A. buildings B. schools C. zoos D. markets
Câu 3: A. disappeared B. decided C. claimed D. freed
Câu 4: A. entertain B. magazine C. industry D. volunteer (Stress)
Câu 5: What time______your work yesterday?
A. did you finish B. are you finishing C. have you finished D. do you finish
Câu 6: I'm not going out yet. I'm waiting_____the rain to stop.
A. for B. at C. on D. with
Câu 7: Lan enjoys watching television after dinner, ?
A. does she B. doesn't she C. did she D. didn't she
Câu 8: ______the TV. There's nothing interesting on.
A. Turn down B. Turn up C. Turn off D. Turn on
Câu 9: ______his frequent absence from class, he passed the test.
A. Because B. Even though C. In spite of D. Therefore
Absence from. vắng mặt
Câu 10: Please spend time______over my composition for spelling errors!
A. read B. reading C. to read D. to reading
Câu 11: When will they finish the of your house?
A. decorate B. decorated C. decoration D. decorating
Câu 12: I'm tired although I stayed up late to do all my homework last night.
A. tired B. although C. to do all D.my homework
Câu 13: Anne felt very happily because she got mark 10 in math.
A. happily B. because C. mark 10 D. in math
Câu 14: Sarah has been working for the company from 2001.
A. has been B. working C. for D. from
Câu 15: There is general ___________ that Vietnamese students lack knowledge of the natural, or manmade, wonders of Viet Nam.
A. recognition B. saying C. accepting D. undertaking
Mình không hiểu a!