3,4x^2 + 8,2x = 0
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a: =>x(7x-5)=0
=>x=0 hoặc x=5/7
b: \(\Leftrightarrow\sqrt{2}x^2-6x=0\)
\(\Leftrightarrow x\left(\sqrt{2}x-6\right)=0\)
hay \(x\in\left\{0;3\sqrt{2}\right\}\)
c: =>x(3,4x+8,2)=0
=>x=0 hoặc x=-82/34=-41/17
d: \(\Leftrightarrow x\left(\dfrac{2}{5}x+\dfrac{7}{3}\right)=0\)
=>x=0 hoặc x=-35/6
Ta có: 3,4 x 2 + 8,2x = 0 ⇔ x(3,4x + 8,2) = 0
⇔ x = 0 hoặc 3,4x + 8,2 = 0 ⇔ x = 0 hoặc x = -(8,2)/(3,4)
Vậy phương trình có hai nghiệm: x 1 = 0, x 1 = -(4,1)/(1,7)
1, \(\frac{x}{4}\) = \(\frac{y}{2}\) = \(\frac{x+y}{4+2}\) = \(\frac{6}{6}\) = 1
=> x = 4; y = 2
2, x : y : z = 6 : 7 : 8 => \(\frac{x}{6}\) = \(\frac{y}{7}\) = \(\frac{z}{8}\)
=> \(\frac{x}{6}\) = \(\frac{y}{7}\) = \(\frac{z}{8}\) = \(\frac{x+y+z}{6+7+8}\) = \(\frac{21}{21}\) = 1
=> x = 6; y = 7; z = 8
3, 4x = 5y => \(\frac{x}{\frac{1}{4}}\) = \(\frac{y}{\frac{1}{5}}\) = \(\frac{x-y}{\frac{1}{4}-\frac{1}{5}}\) = \(\frac{1}{\frac{1}{20}}\) = 20
=> x = 5; y = 4
a: \(=13.45\left(56.78-47.78+1\right)=13.45\cdot10=134.5\)
b: \(=\dfrac{40.4\left(2.5+7.5\right)}{203.8-1.8}=\dfrac{40.4\cdot10}{202}=2\)
c: \(=A\cdot\left(320-320\right)=0\)
d: \(=3.4\left(9+1\right)=3.4\cdot10=34\)
e: \(=1.2\left(21.3+27.7\right)+49\cdot0.8\)
=49*2
=98
f: \(=23.24\left(5.8-4.7-1\right)=23.24\cdot0.1=2.324\)
a) \(56,78\times13,45-13,45\times47,48+13,45\)
\(=13,45\times\left(56,78-47,78+1\right)\)
\(=13,45\times10\)
\(=134,5\)
b) Em ghi đề lại cho rõ ràng
c) \(\left(100+101+102+...+999+1000\right)\times\left(320-160:\dfrac{1}{2}\right)\)
\(=\left(100+101+102+...+999+1000\right)\times\left(320-320\right)\)
\(=\left(100+101+102+...+999+1000\right)\times0\)
\(=0\)
d) \(3,4\times\left(16,35-7,35\right)+0,125\times3,4\times8\)
\(=3,4\times9+3,4\times1\)
\(=3,4\times\left(9+1\right)\)
\(=3,4\times10\)
\(=34\)
e) \(1,2\times21,3+1,2\times27,7+49\times0,8\)
\(=1,2\times\left(21,3+27,7\right)+49\times0,8\)
\(=1,2\times49+49\times0,8\)
\(=49\times\left(1,2+0,8\right)\)
\(=49\times2\)
\(=98\)
f) \(23,24\times5,8-23,24\times4,7-15,24-8\)
\(=23,24\times\left(5,8-4,7\right)-23,24\)
\(=23,24\times1,1-23,24\)
\(=23,24\times\left(1,1-1\right)\)
\(=23,24\times0,1\)
\(=2,324\)
a) 56,78 x 13,45 - 13,45 x 47,78 + 13,45
= 13,45 x ( 56,78 - 47,78 + 1 )
= 13,45 x 10
= 134,5.
= 1419
3.4x^2+8.2x=0
<=>x(3.4x+8.2)=0
<=>x=0 hoặc 3.4x+8.2=0
<=>x=0 hoặc x=-8.2/3.4=-41/17
3,4x2 + 8,2x = 0
<=> x(3,4x + 8,2) = 0
<=> \(\hept{\begin{cases}x=0\\3,4x+8,2=0\end{cases}\hept{\begin{cases}x=0\\x\approx2,41\end{cases}}}\)