(4x-3)x=-125

4x.x-3x=-125

5x-3x=-125

2x=-125

x=-125:2

x=-62,5

62,5

\(\left(3-4x\right)^3=-125\)

\(\Rightarrow\left(3-4x\right)^3=\left(-5\right)^3\)

\(\Rightarrow3-4x=-5\)

\(\Rightarrow4x=8\)

\(\Rightarrow x=2\)

Vậy x = 2

\(\left(3-4x\right)^3=-125< =>\left(3-4x\right)^3=-5^3< =>3-4x=-5\)

\(< =>-4x=-8< =>x=2\)

Vậy x=2

373737.43 - 434343.37 phần 
  2 mũ 2016 - 2 mũ 2015 

\(\dfrac{x^2+4x-12}{2-x}+\dfrac{x^3-125}{x-5}=15\)

\(\dfrac{x^2-2x+6x-12}{-\left(x-2\right)}+\dfrac{\left(x-5\right)\left(x^2+5x+25\right)}{x-5}=15\)

\(\dfrac{x\left(x-2\right)+6\left(x-2\right)}{-\left(x-2\right)}+x^2+5x+25=15\)

\(\dfrac{\left(x-2\right)\left(x+6\right)}{-\left(x-2\right)}+x^2+5x+25=15\)

\(-x-6+x^2+5x+25=15\)

\(x^2+4x+19=15\)

\(x^2+4x+19-15=0\)

\(x^2+4x+4=0\)

\(\left(x+2\right)^2=0\)

\(x+2=0\)

\(x=-2\)

x=-2 nha

(4x-3)⁴=(4x-3)²

\(\Rightarrow\)(4x-3)⁴ - (4x-3)²=0

\(\Rightarrow\)(4x-3)².[(4x-3)²-1]=0

\(\Rightarrow\)(4x-3)²-1=0:(4x-3)²

\(\Rightarrow\)(4x-3)²-1=0

\(\Rightarrow\)(4x-3)²=0+1

\(\Rightarrow\)(4x-3)²=1

\(\Rightarrow\)(4x-3)²=1²

\(\Rightarrow\)4x-3=1

\(\Rightarrow\)4x=1+3

\(\Rightarrow\)x=4:4

\(\Rightarrow\)x=1

(x-1)³=125

\(\Rightarrow\)(x-1)³=5³

\(\Rightarrow\)x-1=5

\(\Rightarrow\)x=5+1

\(\Rightarrow\)x=6

2^x+2 - 2^x=96

\(\Rightarrow\)2^x. 4 - 2^x=96

\(\Rightarrow\)2^x . (4-1) = 96

\(\Rightarrow\)2^x . 3 =96

\(\Rightarrow\)2^x = 96:3

\(\Rightarrow\)2^x = 32

\(\Rightarrow\)2^x = 2⁵

^{\(\Rightarrow\)x =5}

\(4x^3+15=47\)

\(\Leftrightarrow4x^3=32\)

\(\Leftrightarrow x^3=8\)

\(\Leftrightarrow x^3=2^3\)

\(\Leftrightarrow x=2\)

\(4.2^x-3=125\)

\(\Leftrightarrow4.2^x=128\)

\(\Leftrightarrow2^x=32\)

\(\Leftrightarrow2^x=2^5\)

\(\Leftrightarrow x=5\)

ok thanks

a) 4x³+15=47

=> 4x³=47-15

=> 4x³=32

=> x³=32:4

=> x³=2³

=> x=2

b) 4.2^x-3=125

=> 4.2^x=125+3

=> 2^x=128:4

=> 2^x=32

=> 2^x=2⁵

=> x=5

4x³ + 15 = 47

4x³ = 47 - 15

4x³ = 32

x³ = 32 : 4

x³ = 8

x³ = 2³

x = 2

b) 4 . 2^x - 3 = 125

4 . 2^x = 125 + 3

4 . 2^x = 128

2^x = 128 : 4

2^x = 32

2^x = 2⁵

x = 5

a) \(4x^3+15=47\)

\(\Rightarrow4x^3=32\)

\(\Rightarrow x^3=8\)

\(\Rightarrow x^3=2^3\)

\(\Rightarrow x=2\)

Vậy \(x=2\)

b) \(4.2^x-3=125\)

\(\Rightarrow4.2^x=128\)

\(\Rightarrow2^x=32\)

\(\Rightarrow2^x=2^5\)

\(\Rightarrow x=5\)

Vậy \(x=5\)

a ) \(4x^3+15=47\)

\(\Leftrightarrow4x^3=32\)

\(\Leftrightarrow x^3=8\)

\(\Leftrightarrow x^3=2^3\)

\(\Leftrightarrow x=3\)

\(4.2^x-3=125\)

\(\Leftrightarrow4.2^x=128\)

\(\Leftrightarrow2^x=32\)

\(\Leftrightarrow2^x=2^5\)

\(\Leftrightarrow x=5\)

ta có -5= -125

=> 4x -3 =-5

=>4x= -2

=>x=-1/2

\(4x^3+15=47\)

\(\Leftrightarrow4x^3=32\)

\(\Leftrightarrow x^3=8\)

\(\Leftrightarrow x=2\)

\(4\cdot2^x-3=125\)

\(\Leftrightarrow4\cdot2^x=128\)

\(\Leftrightarrow2^x=32\)

\(\Leftrightarrow2^x=2^5\)

\(\Leftrightarrow x=5\)

4x³ + 15 = 47

=> 4x³ = 47 - 15 = 32

=> x³ = 32 : 4 = 8 = 2³

=> x = 2 

4.2^x - 3 = 125

=> 4.2^x = 125 + 3 = 128

=> 2^x = 128 : 4 = 32 = 2⁵

=>x = 5

x=5 hả bn