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17 tháng 2 2020

bài khó quá bạn ạ

17 tháng 2 2020

1+1=2

2+2=4

3+3=6

1 tháng 9 2021

11 ;  2 ; 5

25 tháng 11 2021

troll ak

25 tháng 11 2021

3+3=6

4+4=8

22222222x101010101010=2244668888886644220

bài cuối khó nhỉ

9 tháng 2 2020

Chọn D

Phép đối xứng qua mặt phẳng (P) biến đường thẳng d thành chính nó khi và chỉ khi d nằm trên (P) hoặc d⊥(P)d⊥(P). Có đúng ko mn, mk nghĩ là thế, ai hc lớp 12 tl hộ mk vs.

AH
Akai Haruma
Giáo viên
22 tháng 2 2017

Câu 17:

\(F(x)=\int \sqrt{\ln^2x+1}\frac{\ln x}{x}dx=\int \sqrt{\ln ^2x+1}\ln xd(\ln x)\)

\(\Leftrightarrow F(x)=\frac{1}{2}\int \sqrt{\ln ^2x+1}d(\ln ^2x)\)

Đặt \(\sqrt{\ln^2 x+1}=t\) \(\Rightarrow \ln ^2x=t^2-1\)

\(\Rightarrow F(x)=\frac{1}{2}\int td(t^2-1)=\int t^2dt=\frac{t^3}{3}+c=\frac{\sqrt{(\ln^2x+1)^3}}{3}+c\)

\(F(1)=\frac{1}{3}\Leftrightarrow \frac{1}{3}+c=\frac{1}{3}\Rightarrow c=0\)

\(\Rightarrow F^2(e)=\left(\frac{\sqrt{\ln ^2e+1)^3}}{3}\right)^2=\frac{8}{9}\)

AH
Akai Haruma
Giáo viên
22 tháng 2 2017

Câu 11)

Đặt \(\sqrt{3x+1}=t\Rightarrow x=\frac{t^2-1}{3}\)

\(\Rightarrow I=\int ^{5}_{1}\frac{dx}{x\sqrt{3x+1}}==\int ^{5}_{1}\frac{d\left ( \frac{t^2-1}{3} \right )}{\frac{t(t^2-1)}{3}}=\int ^{4}_{2}\frac{2tdt}{t(t^2-1)}=\int ^{4}_{2}\frac{2dt}{(t-1)(t+1)}\)

\(=\int ^{4}_{2}\left ( \frac{dt}{t-1}-\frac{dt}{t+1} \right )=\left.\begin{matrix} 4\\ 2\end{matrix}\right|(\ln|t-1|-\ln|t+1|)=2\ln 3-\ln 5\)

\(\Rightarrow a=2,b=-1\Rightarrow a^2+ab+3b^2=5\)

Đáp án C

Câu 20)

Ta có:

\(I=\int ^{x}_{\frac{1}{e}}\frac{\ln t+1}{t}dt=\int ^{x}_{\frac{1}{e}}(\ln t+1)d(\ln t)=\int ^{x}_{\frac{1}{e}}\ln td(\ln t)+\int ^{x}_{\frac{1}{e}}d(\ln t)\)

\(=\left.\begin{matrix} x\\ \frac{1}{e}\end{matrix}\right|\left ( \ln t+\frac{\ln^2t}{2}+c \right )=\left ( \ln x+\frac{\ln^2x}{2} \right )+\frac{1}{2}=18\leftrightarrow \ln x+\frac{\ln ^2x}{2}=\frac{35}{2}\)

\(\Rightarrow\left[\begin{matrix}x=e^{-7}\\x=e^5\end{matrix}\right.\)

Đáp án A.

23 tháng 5 2019

trả lời:

mình ko biết

mà bạn là gái hay trai

23 tháng 5 2019

KO

ĐĂNG

CÂU

HỎI

LINH

TINH

TRÊN

DIỄN

ĐÀN

MAGICPENCIL

HÃY LUÔN :-)

26 tháng 10 2019

suốt đầu năm mà có đứa nào tl dc

4 tháng 2 2020

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4 tháng 2 2020

Thui khỏi bt lm òi * nhắn lun ko bt cho nhanh lại cn lm màu *