54x(-48)-43x48
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Trả lời:
5, x2 - y2 + 4x + 4
= ( x2 + 4x + 4 ) - y2
= ( x + 2 )2 - y2
= ( x + 2 - y ) ( x + 2 + y )
6, x2 + 2x - 4y2 - 4y
= ( x2 - 4y2 ) + ( 2x - 4y )
= ( x - 2y ) ( x + 2y ) + 2 ( x - 2y )
= ( x - 2y ) ( x + 2y + 2 )
7, 3x2 - 4y + 4x - 3y2
= ( 3x2 - 3y2 ) + ( 4x - 4y )
= 3 ( x2 - y2 ) + 4 ( x - y )
= 3 ( x - y ) ( x + y ) + 4 ( x - y )
= ( x - y ) [ 3 ( x + y ) + 4 ]
= ( x - y ) ( 3x + 3y + 4 )
8, x4 - 6x3 + 54x - 81
= ( x4 - 81 ) - ( 6x3 - 54x )
= ( x2 - 9 ) ( x2 + 9 ) - 6x ( x2 - 9 )
= ( x2 - 9 ) ( x2 + 9 - 6x )
= ( x - 3 ) ( x + 3 ) ( x - 3 )2
= ( x - 3 )3 ( x + 3 )
a, \(x^2-y^2+4x+4=\left(x+2\right)^2-y^2=\left(x+2-y\right)\left(x+2+y\right)\)
b, \(x^2+2x-4y^2-4y=\left(x-2y\right)\left(x+2y\right)+2\left(x-2y\right)=\left(x-2y\right)\left(x+2+2y\right)\)
c, \(3x^2-4y+4x-3y^2=3\left(x-y\right)\left(x+y\right)-4\left(y-x\right)=\left(x-y\right)\left(3x+3y+4\right)\)
d, \(x^4-6x^3+54x-81=\left(x^2+9\right)\left(x-3\right)\left(x+3\right)-6x\left(x^2-9\right)\)
\(=\left(x-3\right)\left(x+3\right)\left(x^2-6x+9\right)=\left(x-3\right)^3\left(x+3\right)\)
54x 10 = 540
54x100 = 5400
54x1000 = 540 00
108x10 = 1080
108x100 = 10800
108x1000 = 108000
690x10 = 6900
690x100 = 69000
690x1000 = 690 000
54 x 10 = 540
54 x 100 = 5400
54 x 1000 = 54000
108 x 10 = 1080
108 x 100 = 10800
108 x 1000 = 108000
690 x 10 = 6900
690 x 100 = 69000
690 x 1000 = 690000
0,8 : (54x 1,25 + ( 108% -252) :31)
=0,8 : (67.5 + ( -250,92) :31)
=0,8 : ( 67.5 -250,92 :31)
=0,8 : ( 67.5 -8.09)
=0,8:59.41
=0.0134
\(\left\{{}\begin{matrix}2x+y=5\\4x-y=7\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}4x+2y=10\\4x-y=7\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}2x+y=5\\\left(4x-4x\right)+\left(2y+y\right)=10-7\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}2x+y=5\\3y=3\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}2x+y=5\\y=1\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}2x+1=5\\y=1\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}2x=4\\y=1\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}x=2\\y=1\end{matrix}\right.\)
Vậy hệ pt có nghiệm duy nhất \(\left(x;y\right)=\left(2;1\right)\)
b: \(9x^2+54+81=\left(3x+9\right)^2\)
c: \(=\left(y-\dfrac{1}{2}\right)^2\)
d: \(=\left(4x^3-3\right)^2\)
Lấy lôgarit theo cơ số 5 hai vế của bất phương trình, ta được:
Chọn C
\(54\cdot\left(-48\right)-43\cdot48\)
\(=48\left(-54-43\right)\)
\(=48\cdot\left(-97\right)=-4656\)
54⋅(−48)−43⋅4854⋅(−48)−43⋅48
=48(−54−43)=48(−54−43)
=48⋅(−97)
=−4656