Ta có bất đẳng thức Bunhiacopski : \(\left(a^2+b^2\right)\left(x^2+y^2\right)\ge\left(ax+by\right)^2\)

Dấu = xảy ra khi \(\dfrac{a}{x}=\dfrac{b}{y}\)

\(\left[\left(a^5\right)^2+\left(b^5\right)^2\right]\left(a^2+b^2\right)\ge\left(a^6+b^6\right)^2\) (1)

\(\left[\left(a^4\right)^2+\left(b^4\right)^2\right]\left[\left(a^2\right)^2+\left(b^2\right)^2\right]\ge\left(a^6+b^6\right)^2\) (2)

Trừ từng vế của 2 bất đẳng thức (1)(2) ta dược : \(\left[\left(a^5\right)^2+\left(b^5\right)^2\right]\left(a^2+b^2\right)-\left[\left(a^4\right)^2+\left(b^4\right)^2\right]\left[\left(a^2\right)^2+\left(b^2\right)^2\right]\ge\left(a^6+b^6\right)^2-\left(a^6+b^6\right)^2\)

\(\Leftrightarrow\) \(\left(a^{10}+b^{10}\right)\left(a^2+b^2\right)-\left(a^8+b^8\right)\left(a^4+b^4\right)\) \(\ge\) 0

\(\Leftrightarrow\) \(\left(a^{10}+b^{10}\right)\left(a^2+b^2\right)\ge\left(a^8+b^8\right)\left(a^4+b^4\right)\)

Dấu bằng xảy ra khi a=b

1, I ( wait ) have been waiting for two hours, but she ( come ) hasn't come yet.
2, He ( not , be ) hasn't been here since Christmas, I wonder where he ( live ) has been living since then.
3, Have You been sleeping ( sleep ) so far? I ( ring ) have rung the bell for last twenty minutes.
4, Mary ( lose ) has lost her hat and she ( look ) has been looking for it until now .
5, Jack ( go ) has been going to Paris for a holiday . He has never ( be ) been there.

Put the verbs into thư present simple or present perfect

7. Is There (be) a lot of thing? I (want) to do for a long time and I(not do) haven't done them.

8. Have You (realize) realized we (know) have known each other for queit a period of time now? And this(be) is the first occation you(ask) have asked me to come out qqith you?

Ta thấy: /2x+1/>_0

=>276-/2x+1/<_276

=>46.6-/2x+1/<_276

=>B<_276

Khi đó: /2x+1/=0=>2x+1=0=>2x=-1=>x=-1/2

Vậy GTLN của B=276 khi x=-1/2

chọn từ khác loại

1. A. and B. but C. so D. although

2. A. healthy B. fit C. well D. sick

3. A. donate B. rubbish C. blood D. money

4. A. blood B. homework C. students D. tutors

1 he said he .....................a friend at the station that day

a is meeting b is going to meet c was meeting d meets

2 the teacher asked me ..........................a passage into vietnamese

a to translate b translate c translating d translated

3 when i rang tessa sometime last week , she said she was busy ........................................

a today b that day c this day d the day

2⁴⁶ < 3³¹