(3x-72).59=4.510
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47.(59 - 71) - 71.( -59 - 47) + 72.59
= 47.59 - 47.71 + 71.59 + 71.47 + 72.59
= (47.59 + 71.59 + 72.59 ) - (47.71 - 47.71)
= 59.(47 + 71 + 72) - 0
= 59.190
= 11210
47. (-12)-71.(-106)+72.59
=-564-7526+4248
=-8087+4248
=-3839
=46+[72+59+11]
=46+262
=272
tính hơn nhanh nên ko có chắc đấp án đúng nha
2. Đặt \(x-1996=t\)
\(\Rightarrow\left(x-1996\right)^3+\left(x-1997\right)^3-1=t^3+\left(t-1\right)^2-1\)
\(=t^3+t^2-2t+1-1=t^3+t^2-2t=t\left(t^2+t-2\right)\)
\(=t.\left[\left(t^2-t\right)+\left(2t-2\right)\right]=t\left[t\left(t-1\right)+2\left(t-1\right)\right]\)
\(=t\left(t-1\right)\left(t+2\right)=\left(x-1996\right)\left(x-1996-1\right)\left(x-1996+2\right)\)
\(=\left(x-1996\right)\left(x-1997\right)\left(x-1994\right)\)
1. Đặt x2 + 4x + 8 = y
bthuc ⇔ y2 + 3xy + 2x2
= y2 + xy + 2xy + 2x2
= ( xy + y2 ) + ( 2x2 + 2xy )
= y( x + y ) + 2x( x + y )
= ( x + y )( y + 2x )
= ( x + x2 + 4x + 8 )( x2 + 4x + 8 + 2x )
= ( x2 + 5x + 8 )( x2 + 6x + 8 )
= ( x2 + 5x + 8 )( x2 + 2x + 4x + 8 )
= ( x2 + 5x + 8 )[ x( x + 2 ) + 4( x + 2 ) ]
= ( x2 + 5x + 8 )( x + 2 )( x + 4 )
2. Đặt t = x - 1996
bthuc ⇔ t3 + ( t - 1 )2 - 1
= t3 + t2 - 2t + 1 - 1
= t3 + t2 - 2t
= t( t2 + t - 2 )
= t( t2 - t + 2t - 2 )
= t( t - 1 )( t + 2 )
= ( x - 1996 )( x - 1996 - 1 )( x - 1996 + 2 )
= ( x - 1996 )( x - 1997 )( x - 1994 )
3. 4( x2 + 15x + 59 )( x2 + 18x + 72 ) - 3x2 < bó tay :)) >
\(41-\dfrac{72}{19-108:\left[59-2\left(3^2-11\cdot2\right)^2\right]}\)
\(=41-\dfrac{72}{19-108:\left[59-2\left(18-22\right)^2\right]}\)
\(=41-\dfrac{72}{19-108:\left[59-2\cdot16\right]}\)
\(=41-\dfrac{72}{19-108:27}\)
\(=41-\dfrac{72}{19-4}=41-\dfrac{72}{15}\)
=41-4,8
=36,2
\(41-72:\left\{19-108:\left[59-2.\left(3^2-11.2\right)^2\right]\right\}\)
\(=41-72:\left\{19-108:\left[59-2.\left(9-22\right)^2\right]\right\}\)
\(=41-72:\left\{19-108:\left[59-2.\left(-13\right)^2\right]\right\}\)
\(=41-72:\left\{19-108:\left[59-2.169\right]\right\}\)
\(=41-72:\left\{19-108:\left[59-338\right]\right\}\)
\(=41-72:\left\{19-108:-279\right\}\)
\(=41-72:\left\{19-\dfrac{-12}{31}\right\}\)
\(=41-72:\dfrac{601}{31}\)
\(=41-\dfrac{2232}{601}\)
\(=\dfrac{22409}{601}\)
a) x - ( 25 + 72 ) = 59 - 81
x - ( 25 + 72 ) = - 22
x - 97 = - 22
x = - 22 + 97
x = 75
b) 3x - ( - 15 ) = - 57 - 93
3x - ( - 15 ) = - 150
3x = - 150 + ( - 15 )
3x = - 165
x = - 165 : 3
x = -55
\(3^{x+2}-3^x=72\)
\(\Rightarrow3^x\cdot\left(3^2-1\right)=72\)
\(\Rightarrow3^x\cdot\left(9-1\right)=72\)
\(\Rightarrow3^x\cdot8=72\)
\(\Rightarrow3^x=\dfrac{72}{8}\)
\(\Rightarrow3^x=9\)
\(\Rightarrow3^x=3^2\)
\(\Rightarrow x=2\)
_____
Xem lại đề
(3x-72).59 = 4.510
=> 3x-49 = 4.510:59 = 4.5 = 20
=> 3x = 20 + 49 = 69
=> x = 69 : 3
=> x = 23
(3X-72).59=4.510
=>3X-72=510:59.4
=>3X-49=5.4
=>3X-49=20
=>3X=20+49
=>3X=69
=>X=69:3
=>X=23