hộ em vớiiii 
K
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23 tháng 8 2021
a)ĐKXĐ:\(x\ge0,x\ne4\)
b)M=\(\dfrac{\sqrt{x}\left(\sqrt{x}+2\right)+\sqrt{x}\left(\sqrt{x}-2\right)}{\left(\sqrt{x}+2\right)\left(\sqrt{x}-2\right)}.\dfrac{x-4}{\sqrt{4x}}\)
M=\(\dfrac{2x}{x-4}.\dfrac{x-4}{\sqrt{4x}}\)=\(\sqrt{x}\)
c) để M>3\(\Rightarrow\)\(\sqrt{x}>3\)\(\Rightarrow x>9\)
23 tháng 8 2021
a: ĐKXĐ: \(\left\{{}\begin{matrix}x>0\\x\ne4\end{matrix}\right.\)
b: Ta có: \(M=\left(\dfrac{\sqrt{x}}{\sqrt{x}-2}+\dfrac{\sqrt{x}}{\sqrt{x}+2}\right)\cdot\dfrac{x-4}{\sqrt{4x}}\)
\(=\dfrac{x+2\sqrt{x}+x-2\sqrt{x}}{\left(\sqrt{x}-2\right)\cdot\left(\sqrt{x}+2\right)}\cdot\dfrac{\left(\sqrt{x}-2\right)\left(\sqrt{x}+2\right)}{2\sqrt{x}}\)
\(=\sqrt{x}\)
c: Để M>3 thì x>9
22 tháng 11 2023
5: \(\left(2x-3\right)^2-16\)
\(=\left(2x-3\right)^2-4^2\)
\(=\left(2x-3-4\right)\left(2x-3+4\right)\)
\(=\left(2x-7\right)\left(2x+1\right)\)
6: \(\left(2x+1\right)^2-\left(\dfrac{1}{2}x-7\right)^2\)
\(=\left(2x+1-\dfrac{1}{2}x+7\right)\left(2x+1+\dfrac{1}{2}x-7\right)\)
\(=\left(\dfrac{3}{2}x+8\right)\left(\dfrac{5}{2}x-6\right)\)
7: \(\left(x+7\right)^2-\left(4x+5\right)^2\)
\(=\left(x+7-4x-5\right)\left(x+7+4x+5\right)\)
\(=\left(-3x+2\right)\left(5x+12\right)\)
8: \(\left(\dfrac{1}{4}x+3\right)^2-\left(4x-\dfrac{1}{4}\right)^2\)
\(=\left(\dfrac{1}{4}x+3-4x+\dfrac{1}{4}\right)\left(\dfrac{1}{4}x+3+4x-\dfrac{1}{4}\right)\)
\(=\left(-\dfrac{15}{4}x+\dfrac{13}{4}\right)\left(\dfrac{17}{4}x+\dfrac{11}{4}\right)\)
9: \(\left(\dfrac{1}{3}x+3\right)^2-\left(4x-\dfrac{2}{3}\right)^2\)
\(=\left(\dfrac{1}{3}x+3-4x+\dfrac{2}{3}\right)\left(\dfrac{1}{3}x+3+4x-\dfrac{2}{3}\right)\)
\(=\left(-\dfrac{11}{3}x+\dfrac{11}{3}\right)\left(\dfrac{13}{3}x+\dfrac{7}{3}\right)\)
\(=-\dfrac{11}{3}\left(x-1\right)\left(\dfrac{13}{3}x+\dfrac{7}{3}\right)\)
10: \(9\left(x+5\right)^2-4\left(2x+8\right)^2\)
\(=\left[3\left(x+5\right)\right]^2-\left[2\left(2x+8\right)\right]^2\)
\(=\left(3x+15\right)^2-\left(4x+16\right)^2\)
\(=\left(3x+15-4x-16\right)\left(3x+15+4x+16\right)\)
\(=\left(-x-1\right)\left(7x+31\right)\)
11: \(\left(x+5\right)^2-25\left(2x+8\right)^2\)
\(=\left(x+5\right)^2-\left[5\left(2x+8\right)\right]^2\)
\(=\left(x+5\right)^2-\left(10x+40\right)^2\)
\(=\left(x+5-10x-40\right)\left(x+5+10x+40\right)\)
\(=\left(-9x-35\right)\left(11x+45\right)\)
12: \(16\left(2x+5\right)^2-9\left(2x-1\right)^2\)
\(=\left[4\left(2x+5\right)\right]^2-\left[3\left(2x-1\right)\right]^2\)
\(=\left(8x+20\right)^2-\left(6x-3\right)^2\)
\(=\left(8x+20+6x-3\right)\left(8x+20-6x+3\right)\)
\(=\left(14x+17\right)\left(2x+23\right)\)
17 tháng 1 2022
1: \(=\left(x+y+x-y\right)\left(x+y-x+y\right)=2x\cdot2y=4xy\)
2: \(=x^3+3x^2y+3xy^2+y^3-x^3+3x^2y-3xy^2+y^3\)
\(=6x^2y+2y^3=2y\left(3x^2+y^2\right)\)
3: \(=x^3+3x^2y+3xy^2+y^3+x^3-3x^2y+3xy^2-y^3\)
\(=2x^3+6xy^2=2x\left(x^2+3y^2\right)\)
4: \(=\left(7-4x+5\right)\left(7+4x-5\right)=\left(12-4x\right)\left(4x+2\right)\)
\(=8\left(3-x\right)\left(2x+1\right)\)
H
17 tháng 4 2021
\(a)C_6H_6 + 3Cl_2 \to C_6H_6Cl_6\\ n_{Cl_2}= \dfrac{2,24}{22,4} = 0,1(mol)\\ n_{C_6H_6} = \dfrac{1}{3}n_{Cl_2} = \dfrac{0,1}{3}(mol)\\ m_{C_6H_6} = \dfrac{0,1}{3}.78 = 26(gam)\\ b) n_{C_6H_6Cl_6} = n_{C_6H_6} = \dfrac{0,1}{3}(mol)\\ m_{C_6H_6Cl_6} = \dfrac{0,1}{3}.291 = 97(gam)\)
KV
19 tháng 12 2023
a) 127 - 2(-2x + 4)² = -1
2(-2x + 4)² = 127 + 1
2(-2x + 4)² = 128
(-2x + 4)² = 128 : 2
(-2x + 4)² = 64
-2x + 4 = 8 hoặc -2x + 4 = -8
*) -2x + 4 = 8
-2x = 8 - 4
-2x = 4
x = 4 : (-2)
x = -2
*) -2x + 4 = -8
-2x = -8 - 4
-2x = -12
x = -12 : (-2)
x = 6
b) -6² - 3.(-4 - x)³ = -39
3(-4 - x)³ = -6² + 39
3(-4 - x)³ = -36 + 39
3(-4 - x)³ = 3
(-4 - x)³ = 3 : 3
(-4 - x)³ = 1
(-4 - x)³ = 1³
-4 - x = 1
x = -4 - 1
x = -5
c) (-7x - 35).(2x² - 32) = 0
-7x - 35 = 0 hoặc 2x² - 32 = 0
*) -7x - 35 = 0
-7x = 0 + 35
-7x = 35
x = 35 : (-7)
x = -5
*) 2x² - 32 = 0
2x² = 0 + 32
2x² = 32
x² = 32 : 2
x² = 16
x = -4; x = 4
Vậy x = -5; x = -4; x = 4
d) (2018 + 2x)(4x² + 8) = 0
2018 + 2x = 0 (do 4x² + 8 > 0)
2x = 0 - 2018
2x = -2018
x = -2018 : 2
x = -1014
e) -145 - 4(3 - 2x)² = -245
4(3 - 2x) = -145 + 245
4(3 - 2x) = 100
3 - 2x = 100 : 4
3 - 2x = 25
2x = 3 - 25
2x = -22
x = -22 : 2
x = -11
g) 4(-x + 1)³ - (-5)² = -525
4(-x + 1)³ - 25 = -525
4(-x + 1)³ = -525 + 25
4(-x + 1)³ = -500
(-x + 1)³ = -500 : 4
(-x + 1)³ = -125
(-x + 1)³ = (-5)³
-x + 1 = -5
-x = -5 - 1
-x = -6
x = 6
mn gấp quá có ai giúp em vớiiii
23 tháng 9 2021
e: Ta có: \(\sqrt{x^2+3x+1}=\sqrt{x+1}\)\(\)
\(\Leftrightarrow x^2+3x=x\)
\(\Leftrightarrow x\left(x+2\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=0\left(loại\right)\\x=-2\left(loại\right)\end{matrix}\right.\)
có làm thì mới có ăn
em kh làm nhưng em có đòi ăn đâu :(