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BT
7
13 tháng 7 2021
1) Ta có: \(\sqrt{2x+5}=\sqrt{3-x}\)
\(\Leftrightarrow2x+5=3-x\)
\(\Leftrightarrow2x+x=3-5\)
\(\Leftrightarrow3x=-2\)
hay \(x=-\dfrac{2}{3}\)
2) Ta có: \(\sqrt{2x-5}=\sqrt{x-1}\)
\(\Leftrightarrow2x-5=x-1\)
\(\Leftrightarrow2x-x=-1+5\)
\(\Leftrightarrow x=4\)
PN
23 tháng 8 2021
3 , \(PT\left(đk:\frac{16}{3}\ge x\ge3\right)< =>x^2-3x=16-3x\)
\(< =>x^2-16=0< =>\left(x-4\right)\left(x+4\right)=0< =>\orbr{\begin{cases}x=4\left(tm\right)\\x=-4\left(ktm\right)\end{cases}}\)
4 , \(PT\left(đk:...\right)< =>2x^2-3=4x-3< =>2x^2-4x=0\)
\(< =>2x\left(x-2\right)=0< =>\orbr{\begin{cases}x=0\left(...\right)\\x=2\left(...\right)\end{cases}}\)
bạn tự tìm đk rồi đối chiếu nhé :P
NV
Nguyễn Việt Lâm
Giáo viên
17 tháng 8 2021
ĐKXĐ:
a. \(\left\{{}\begin{matrix}x+1\ge0\\x^2-3x+2\ne0\end{matrix}\right.\) \(\Leftrightarrow\left\{{}\begin{matrix}x\ge-1\\x\ne\left\{1;2\right\}\end{matrix}\right.\)
Hay \(D=[-1;1)\cup\left(1;2\right)\cup\left(2;+\infty\right)\)
b. \(\left\{{}\begin{matrix}x+2\ge0\\1-x\ne0\end{matrix}\right.\) \(\Leftrightarrow\left\{{}\begin{matrix}x\ge-2\\x\ne1\end{matrix}\right.\)
c. \(\left\{{}\begin{matrix}1+x\ge0\\1-x\ge0\end{matrix}\right.\) \(\Leftrightarrow-1\le x\le1\)
d. \(\left\{{}\begin{matrix}1-4x^2\ge0\\x^2-2x\ne0\end{matrix}\right.\) \(\Leftrightarrow\left\{{}\begin{matrix}-\dfrac{1}{2}\le x\le\dfrac{1}{2}\\x\ne0\end{matrix}\right.\)
ND
1
3K
3
R
24 tháng 11 2021
a) \(12=2^2.3\) \(60=2^2.3.5\)
\(ƯCLN\left(12;60\right)=2^2=4\)
b) \(24=2^2.3.2\)
24 tháng 11 2021
12 = 22 x 3
60 = 22 x 3 x 5
ƯCLN (12, 60) = 22 . 3 = 12
24 = 23 x 3
88 = 23 x 11
ƯCLN (24, 88) = 23 = 8
96 = 25 x 3
224 = 25 x 7
ƯCLN (96, 224) = 25 = 32
34 = 2 x 17
96 = 25 x 3
ƯCLN (34, 96) = 2
10 tháng 12 2020
1:
max:=a;
if max<b then max:=b;
2:
min:=a;
if min>b then min:=b;
3: if (x=sqr(a)+sqr(b)) and (a<0) then writeln(x);
if (x=sqrt(b)+sqrt(a)) and (a>0) then writeln(x);
13 tháng 9 2021
1. I was late for the meeting because of the heavy traffic .
2. He is very intelligent due to the reason that he reads a lot of books.
3. The car is too expensive so I can't buy it.
4. I broke my mother's favorite vase so she became very angry.
5. There are too many tall building, so we can't see the moon.
6. Since he was lazy, he fell the exam.
7. Because the air is polluted, so many people have breathing problems.
8.They never go out, so they don't know anything outside.
9. Because their parents don't allow them waste money, the children have a lot of saving money.
10. The student's parents always understand them so they feel happy.
NH
0
WD
3
\(\frac{tan2x-tanx}{tan2xtanx}=\frac{1}{tanx}-\frac{1}{tan2x}=\frac{1}{tanx}-\frac{1-tan^2x}{2tanx}=\frac{1+tan^2x}{2tanx}=\frac{1+\frac{sin^2x}{cos^2x}}{\frac{2sinx}{cosx}}\)
\(=\frac{1}{2cosxsinx}=\frac{1}{sin2x}\)
suy ra \(\frac{tan2xtanx}{tan2x-tanx}=sin2x\).