\(g'\left(x\right)=\left(-2x\right)'\cdot f'\left(-2x\right)\)

\(=-2\cdot f'\left(-2x\right)\)

\(=-2\left(-2x^2-4x\right)\)

\(=4x^2+8x\)

\(g''\left(x\right)=4\cdot2x+8=8x+8\)

g'(x)=0

=>4x(x+2)=0

=>x=0 hoặc x=-2

Khi x=0 thì \(g''\left(x\right)=8\cdot0+8=8\)>0

=>Khi x=0 thì g(x) đạt giá trị cực đại

Khi x=-2 thì \(g''\left(x\right)=8\cdot\left(-2\right)+8=-8< 0\)

=>Khi x=-2 thì g(x) không đạt giá trị cực đại

Vậy: G(x) đạt giá trị cực đại tại x=0

Câu 44: C

Câu 45: C

44 If I had known your name, I could have introduced you with my friends

45 If the driver in front hadn't stopped so quickly, the accident wouldn't have happened

46 If I had known Geogre wanted to get up early, I would have waken him 

47 If Jim hadn't lent me the money, I wouldn't have been able to buy the motorbike 

48 If she hadn't been wearing the seat belt, she wouldn't have injured (câu này sao ta)

49 If she had had enough money on her, she would have bought the coat

50 If....(tên ai đó) hadn't gone to the bus stop in time, she would have late for the interview

51 If.......hadn't recommened the hotel to us, we wouldn't have stayed at this hotel

52 If you had had breakfast, you wouldn't be hungry now

44C - 45A - 46C - 47D - 48D

 
 a.chia cho 15 dư 1
 
b. chia cho 15 dư 14
 
 c.chia hết cho 81

k mình nha

chia 15 dư 1

chia cho 15 dư 14

chia hết cho 81 

tích mk đi dù chỉ 1 cái

a) Chia hết cho 15 dư 1

b) chia 15 dư 14

c) chia hết 81

<=> 18 - 3 + x - 44 + x =55

<=> x + x = 55 - 18 + 3 + 44

<=> 2x  =  84

<=> x   =   84  : 2

<=> x   =   42

Trả lời :.....................................................

18 + ( -3 + x ) - ( 44 - x ) = 55

\(\Leftrightarrow x+x=55-18+3+44\)

\(\Leftrightarrow2x=84\)

\(\Leftrightarrow x=84:2\)

\(\Leftrightarrow x=42\)

chua hoc den noi nha

là câu B đấy bạn

B