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ak nhầm

chịu

*\(M+\left(5x^2-2xy\right)=6x^2+9xy-y^2\)

\(M=6x^2+9xy-y^2-\left(5x^2-2xy\right)\)

\(M=6x^2+9xy-y^2-5x^2+2xy\)

\(M=\left(6-5\right)x^2+\left(9+2\right)xy-y^2\)

\(M=x^2+11xy-y^2\)

* \(\left(2x-5\right)^{2018}+\left(3y+4\right)^{2020}\le0\)

Ta có : \(\hept{\begin{cases}\left(2x-5\right)^{2018}\ge0\forall x\\\left(3y+4\right)^{2020}\ge0\forall y\end{cases}\Rightarrow}\left(2x-5\right)^{2018}+\left(3y+4\right)^{2020}\ge0\forall x,y\)

Mà đề cho \(\left(2x-5\right)^{2018}+\left(3y+4\right)^{2020}\le0\)

=> \(\left(2x-5\right)^{2018}+\left(3y+4\right)^{2020}=0\)

=> \(\hept{\begin{cases}2x-5=0\\3y+4=0\end{cases}\Rightarrow}\hept{\begin{cases}x=\frac{5}{2}\\y=-\frac{4}{3}\end{cases}}\)

Thay x = 5/2 ; y = -4/3 vào M ta được :

\(M=\left(\frac{5}{2}\right)^2+11\cdot\frac{5}{2}\cdot\left(-\frac{4}{3}\right)-\left(-\frac{4}{3}\right)^2\)

\(M=\frac{25}{4}+\frac{-110}{3}-\frac{16}{9}\)

\(M=\frac{-1159}{36}\)

Vậy giá trị của M = -1159/36 khi x = 5/2 ; y = -4/3

Không chắc nha 

What help?

a: Xét ΔHAB và ΔHDB có 

HA=HD

AB=DB

HB chung

Do đó: ΔHAB=ΔHDB

b: Xét ΔBAI và ΔBDI có

BA=BD

\(\widehat{ABI}=\widehat{DBI}\)

BI chung

Do đó: ΔBAI=ΔBDI

Suy ra: \(\widehat{BAI}=\widehat{BDI}=90^0\)

hay ID⊥BC

'đóng cửa sổ lại, làm ơn' cô ấy nói với tôi

'làm ơn giúp tôi với, minh' cô ấy nói với tôi

đừng hút thuốc, cô ấy đã nói với tôi

làm ơn đừng đến sau, cô ấy nói

1 She told me to close the window

2 She told Minh to help her

3 She told me not to smoke

4 She told Hoa not to be later

Old man:  Can you please do me a favor?   Ba: ...............

       A. Yes. Please help me                                       B. Sure. How can I help you?

       C. Yes, you can                                                     D. No, you can't

 Câu 7. The children can look after ............................... for a few days.

       A. them                           B. they                          C. themself                   D. themselves

 Câu 8. My grandfather used ____________ us to the zoo when he was alive.

       A. took                             B. to take                     C. taking                       D. take

 Câu 9. Choose the underlined word or phrase in each sentence  that  needs correcting.

         The armchair is in the living-room among the television and the sofa.

                       A        B                                        C                                 D

Câu 10. My hometown is getting more modern and .....................

       A. more noisy                B. noisier                     C. noisiest                     D. more noisier

 Câu 11. The water wasn't ____________ in.

       A. clear enough for swimming                         B. enough clear for swimming

       C. enough clear to swim                                    D. clear enough to swim

 Câu 12. Choose the word that has the underlined part pronounces  differently

       A. looked                        B. phoned                   C. missed                      D. watched

 Câu 13. Don't come in. Pleased wait ____________ for your turn.  

       A. outside                       B. inside                       C. downstairs              D. upstairs

 Câu 14. We must be there....................7.30 and 10.30.

       A. between                     B. at                              C. after                          D. before

 Câu 15. His father is very proud  ________  him.

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

 Câu 16. They …………….. in that house for 3 years.

       A. have lived                  B. live                            C. lived                          D. are living   

 Câu 17. Choose the word that has a different stress pattern from the others.

       A. plentiful                      B. generous                C. volunteer                 D. sociable

What's your question

Thank you but i'm okay! Sorry! I'm very sorry!

làm đúng và nhanh mình tặng coin cho 

câu 13: 2222

câu 14: thứ tư

câu 15: 88

câu 19:980

câu  20:7

câu 18: 19/10