Ai chỉ mik vs
K
Khách
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Những câu hỏi liên quan
DT
Đỗ Thanh Hải
CTVVIP
21 tháng 8 2021
1 has changed
2 are driving
3 were made
4 went - saw
5 finish
6 have been
7 weren't
8 will write
9 doing
10 to work
11 will clean
12 tastes - are
13 has become
14 went
15 is learning
16 won't be
17 is cut
18 eats
19 stewing
20 to drink
21 is organised
22 built
23 were made
14 was set
25 haven't done
26 is speaking
27 are spoken
3 tháng 10 2021
a) \(\left(2x+1\right)^2-4\left(x+2\right)^2=9\\ \Rightarrow\left(2x+1\right)^2-\left[2\left(x+2\right)\right]^2=9\\ \Rightarrow\left(2x+1-2x-4\right)\left(2x+1+2x+4\right)=9\\ \Rightarrow-3\left(4x+5\right)=9\\ \Rightarrow-12x-15=9\\ \Rightarrow x=-2\)
b) \(\left(x+3\right)^2-\left(x-4\right)\left(x+8\right)=1\\ \Rightarrow x^2+6x+9-\left(x^2+4x-32\right)=1\\ \Rightarrow x^2+6x+9-x^2-4x+32=1\\ \Rightarrow2x=-40\\ \Rightarrow x=-20\)
3 tháng 10 2021
\(a,\Rightarrow4x^2+4x+1-4x^2-16x-16=9\\ \Rightarrow-12x=24\Rightarrow x=-2\\ b,\Rightarrow x^2+6x+9-x^2-4x+32=1\\ \Rightarrow2x=-40\Rightarrow x=-20\\ c,\Rightarrow3x^2+12x+12+4x^2-4x+1-7x^2+63=36\\ \Rightarrow8x=-40\Rightarrow x=-5\\ d,\Rightarrow x^3-27+4x-x^3=1\\ \Rightarrow4x=28\Rightarrow x=7\\ e,\Rightarrow x^3+3x^2+3x+1-x^3+3x^2-3x+1-6x^2+12x-6=-19\\ \Rightarrow12x=-15\Rightarrow x=-\dfrac{5}{4}\)
MP
1
5 tháng 10 2021
Bài 3:
a: \(M=x^2-4x+5\)
\(=x^2-4x+4+1\)
\(=\left(x-2\right)^2+1\ge1\forall x\)
Dấu '=' xảy ra khi x=2
b: \(N=y^2-y-3\)
\(=y^2-2\cdot y\cdot\dfrac{1}{2}+\dfrac{1}{4}-\dfrac{13}{4}\)
\(=\left(y-\dfrac{1}{2}\right)^2-\dfrac{13}{4}\ge-\dfrac{13}{4}\forall y\)
Dấu '=' xảy ra khi \(y=\dfrac{1}{2}\)
21 tháng 10 2021
a: \(x^2-9y^2=\left(x-3y\right)\left(x+3y\right)\)
c: \(\left(x+5\right)^2-16=\left(x+1\right)\left(x+9\right)\)
e: \(\left(2x+3\right)^2-\left(x-7\right)^2\)
\(=\left(2x+3+x-7\right)\left(2x+3-x+7\right)\)
\(=\left(3x-4\right)\left(x+10\right)\)
K
0
T
1
YD
3
26 tháng 8 2018
Đừng đăng câu hỏi lung tung k liên quan đến toán và tiếng việt
Chúc bn hc tốt
Tk nha
PC
1
\(K=\sqrt{4x^2-4x+1} +\sqrt{4x^2-12x+9}+2\)
\(\)\(K=\sqrt{\left(2x-1\right)^2}+\sqrt{\left(2x-3\right)^2}+2\)
\(K=\left|2x-1\right|+\left|2x-3\right|+2\)
\(K=\left|2x-1\right|+\left|-2x+3\right|+2\ge\left|2x-1-2x+3\right|+2\)
\(\Rightarrow K\ge\left|2\right|+2\ge4\)
\(\Rightarrow MinK=4\) \(dấu"="\) \(xảy\) \(ra\Leftrightarrow\left(2x-1\right)\left(-2x+3\right)\ge0\Leftrightarrow\dfrac{1}{2}\le x\le\dfrac{3}{2}\)