2/5x3/4+1/4x2/5
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11 tháng 4 2023
=>5x^3+4x^2+3x+3-4+x+4x^2-5x^3=5
=>8x^2+4x-1-5=0
=>8x^2+4x-6=0
=>4x^2+2x-3=0
=>\(x=\dfrac{-1\pm\sqrt{13}}{4}\)
14 tháng 2 2022
1: \(\Leftrightarrow\left(x-3\right)\left(x+3\right)-\left(x-3\right)\left(5x+2\right)=0\)
\(\Leftrightarrow\left(x-3\right)\left(-4x+1\right)=0\)
hay \(x\in\left\{3;\dfrac{1}{4}\right\}\)
2: \(\Leftrightarrow\left(x-1\right)\left(x^2+x+1\right)-\left(x-1\right)\left(x^2-2x+16\right)=0\)
\(\Leftrightarrow\left(x-1\right)\left(x^2+x+1-x^2+2x-16\right)=0\)
\(\Leftrightarrow\left(x-1\right)\left(3x-15\right)=0\)
hay \(x\in\left\{1;5\right\}\)
3: \(\Leftrightarrow\left(x-1\right)\left(4x^2-1\right)=0\)
\(\Leftrightarrow\left(x-1\right)\left(2x-1\right)\left(2x+1\right)=0\)
hay \(x\in\left\{1;\dfrac{1}{2};-\dfrac{1}{2}\right\}\)
4: \(\Leftrightarrow x^2\left(x+4\right)-9\left(x+4\right)=0\)
\(\Leftrightarrow\left(x+4\right)\left(x-3\right)\left(x+3\right)=0\)
hay \(x\in\left\{-4;3;-3\right\}\)
5: \(\Leftrightarrow\left[{}\begin{matrix}3x+5=x-1\\3x+5=1-x\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}2x=-6\\4x=-4\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=-3\\x=-1\end{matrix}\right.\)
6: \(\Leftrightarrow\left(6x+3\right)^2-\left(2x-10\right)^2=0\)
\(\Leftrightarrow\left(6x+3-2x+10\right)\left(6x+3+2x-10\right)=0\)
\(\Leftrightarrow\left(4x+13\right)\left(8x-7\right)=0\)
hay \(x\in\left\{-\dfrac{13}{4};\dfrac{7}{8}\right\}\)
14 tháng 2 2022
1.
\(\Leftrightarrow\left(x-3\right)\left(x+3\right)=\left(x-3\right)\left(5x-2\right)\)
\(\Leftrightarrow x+3=5x-2\)
\(\Leftrightarrow4x=5\Leftrightarrow x=\dfrac{5}{4}\)
2.
\(\Leftrightarrow\left(x-1\right)\left(x^2+x+1\right)=\left(x-1\right)\left(x^2-2x+16\right)\)
\(\Leftrightarrow x^2+x+1=x^2-2x+16\)
\(\Leftrightarrow3x=15\Leftrightarrow x=5\)
3.
\(\Leftrightarrow4x^2\left(x-1\right)-\left(x-1\right)=0\)
\(\Leftrightarrow\left(x-1\right)\left(4x^2-1\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=1\\x=\dfrac{1}{2};x=-\dfrac{1}{2}\end{matrix}\right.\)
NH
2
S
9 tháng 1 2017
a) C1 : 2/5 x 3/7 + 2/7 x 4/7
= 2/5 x (3/7 + 4/7)
= 2/5 x 1
= 2/5
C2 : 2/5 x 3/7 + 2/5 x 4/7
= 6/35 + 8/35
= 2/5
b) (2/3 - 4/7) x 5/5
= 2/21 x 5/5
= 2/21
C2 : (2/3 - 4/7) x 5/5
= 2/3 x 1 - 4/7 x 1
= 2/3 - 4/7
= 2/21
c) 3/4 x 2/5 - 3/4 x 2/7
= 3/4 x (2/5 - 2/7)
= 3/4 x 4/35
= 3/35
C2 : 3/4 x 2/5 - 3/4 x 2/7
= 3/10 - 3/14
= 3/35
9 tháng 1 2017
a,
Cách 1
\(\frac{2}{5}\times\frac{3}{7}+\frac{2}{5}\times\frac{4}{7}\)
\(=\frac{6}{35}+\frac{8}{35}\)
\(=\frac{2}{5}\)
Cách 2 :
\(\frac{2}{5}\times\frac{3}{7}+\frac{2}{5}\times\frac{4}{7}\)
\(=\frac{2}{5}\times\left(\frac{3}{7}+\frac{4}{7}\right)\)
\(=\frac{2}{5}\times1\)
\(=\frac{2}{5}\)
b,
Cách 1 :
\(\left(\frac{2}{3}-\frac{4}{7}\right)\times\frac{5}{5}\)
\(=\frac{2}{21}\times1\)
\(=\frac{2}{21}\)
Cách 2 :
\(\left(\frac{2}{3}-\frac{4}{7}\right)\times\frac{5}{5}\)
\(=\frac{2}{3}\times\frac{5}{5}-\frac{4}{7}\times\frac{5}{5}\)
\(=\frac{2}{3}-\frac{4}{7}\)
\(=\frac{2}{21}\)
c,
Cách 1 :
\(\frac{3}{4}\times\frac{2}{5}-\frac{3}{4}\times\frac{2}{7}\)
\(=\frac{3}{10}-\frac{3}{14}\)
\(=\frac{3}{35}\)
Cách 2 :
\(\frac{3}{4}\times\frac{2}{5}-\frac{3}{4}\times\frac{2}{7}\)
\(=\frac{3}{4}\times\left(\frac{2}{5}-\frac{2}{7}\right)\)
\(=\frac{3}{4}\times\frac{4}{35}\)
\(=\frac{3}{35}\)
Mk nhanh nhất đó
Đúng 100%
Tk mk mk tk lại
Cảm ơn bạn nhiều
Thank you very much
( ^ _ ^ )
TH
2
5 tháng 3 2022
\(A=5x^3-7x^2+3x^3-4x^2+x^2-x^3+5x-1=7x^3-10x^2+5x-1\)
\(B=5x^3+3x^2-7x^4-5x^3+4x^2-x^4+3=-8x^4+7x^2+3\)
DM
1
3 tháng 8 2018
\(a,\frac{2}{5}:\frac{6}{5}+\frac{3}{4}.\frac{12}{5}\)
=\(\frac{2}{5}.\frac{5}{6}+\frac{9}{5}\)
=\(\frac{1}{3}+\frac{9}{5}\)
=\(\frac{32}{5}\)
b) \(\frac{17}{5}.\frac{3}{5}.\frac{17}{5}.\frac{2}{5}\)
=\(\frac{17}{5}.\left(\frac{3}{5}.\frac{2}{5}\right)\)
=\(\frac{17}{5}.\frac{6}{25}\)
=\(\frac{102}{125}\)
c)\(\frac{1}{4}+\frac{3}{4}.\frac{2}{3}-\frac{1}{2}\)
=\(\frac{1}{4}+\frac{1}{2}-\frac{1}{2}\)
=\(\frac{1}{4}\)
d)\(\frac{6}{7}+\frac{5}{8}:5\)
=\(\frac{6}{7}+\frac{5}{8}.\frac{1}{5}\)
=\(\frac{6}{7}+\frac{1}{8}\)
=\(\frac{48}{56}+\frac{7}{56}\)
=\(\frac{55}{56}\)
tk nhé bn!
HN
29 tháng 8 2021
a) \(2x\left(x^2-7x-3\right)=2x.x^2-2x.7x-2x.3=2x^3-14x^2-6x\)
b) \(\left(-2x^3+y^2-7xy\right)4xy^2=\left(-2x^3\right)4xy^2+y^24xy^2-7xy.4xy^2=-8x^4y^2+4xy^4-28x^2y^3\)
c) \(\left(-5x^3\right)\left(2x^2+3x-5\right)=-5x^32x^2-5x^33x-5x^3.-5=-10x^5-15x^4+25x^3\)
d) \(\left(2x^2-xy+y^2\right)\left(-3x^3\right)=-3x^32x^2-3x^3.-xy-3x^3y^2=-6x^5+3x^4y-3x^3y^2\)
HN
29 tháng 8 2021
e) \(\left(x^2-2x+3\right)\left(x-4\right)=x\left(x^2-2x+3\right)-4\left(x^2-2x+3\right)=x^3-2x^2+3x-4x^2+8x-12=x^3-6x^2+11x-12\)
f) \(\left(2x^3-3x-1\right)\left(5x+2\right)=5x\left(2x^3-3x-1\right)+2\left(2x^3-3x-1\right)=10x^4-15x^2-5x+4x^3-6x-2=10x^4+4x^3-15x^2-11x-2\)
.
\(\dfrac{2}{5}\times\dfrac{3}{4}+\dfrac{1}{4}\times\dfrac{2}{5}\\ =\dfrac{2}{5}\times\left(\dfrac{1}{4}+\dfrac{3}{4}\right)\\ =\dfrac{2}{5}\times1\\ =\dfrac{2}{5}\)