a) |2x-3|+x=21

|2x-3|=21-x

\(\Rightarrow\)\(\orbr{\begin{cases}2x-3=21-x\\2x-3=-\left(21-x\right)\end{cases}}\)

TH1: 2x-3=21-x

2x-x=21+3

x=24

TH2: 2x-3=-(21-x)

2x-3 = -21+x

2x-x=-21+3

x=-18

Vậy x \(\varepsilon\){-18;24}

tao ko biết làm ok

\(x:2=x:3\)

\(\Rightarrow x=0\)

\(x:2=x:3\)

\(\Leftrightarrow\left(x:2\right)-\left(x:3\right)=0\)

\(\Leftrightarrow\left(x.\frac{1}{2}\right)-\left(x.\frac{1}{3}\right)=0\)

\(\Leftrightarrow x.\left(\frac{1}{2}-\frac{1}{3}\right)=0\)

\(\Leftrightarrow x.\frac{1}{6}=0\)

\(\Leftrightarrow x=0\)

X = 0 nhá

ví số dư của f(x) chia cho g(x)=x-a là f(a)

=> Để f(x) chia hết cho x-1 => f(1)=0

                                        =>f(1)=1^3-a.1^2+2.1-5=0

                                        =>f(1)=1-a+2-5=0

                                        =>f(1)=-a-2=0 => -a=2 =>a=-2

 

P(x) + Q(x) = x³ - 6x + 2 + 2x² - 4x³ + x - 5

                = x³ - 4x³ + 2x² + (-6x + x) + 2 - 5

               = -3x³ + 2x² - 5x - 3

P(x) - Q(x) = (x³ - 6x + 2) - (2x² - 4x³ + x - 5)

               = x³ - 6x + 2 - 2x² + 4x³ - x + 5

              = x³ + 4x³ - 2x² + (-6x - x) + 2 + 5

             = 4x³ - 2x² - 7x + 7

t i c k nhé

Lời giải:
$45-3(7+x)=6$

$3(7+x)=45-6=39$

$7+x=39:3=13$

$x=13-7=6$

27^x=3^x+2

\(\Rightarrow3^{3x}=3^{x+2}\)

\(\Rightarrow3x=x+2\)

\(\Rightarrow3x-x=2\)

\(\Rightarrow2x=2\)

\(\Rightarrow x=1\)

Vậy x=1

Chúc bn học tốt

27^x = 3^x+2

(3³)^x=3^x+2

3x=x+2

3x-x=2

2x=2

  x=2:2

  x=1

Vậy x=1

Câu 1:

\(3x\left(12x+4\right)+9x\left(4x+3\right)\)

\(\Leftrightarrow3x\left(12x+4\right)+3x\left[3.\left(4x+3\right)\right]\)

\(\Leftrightarrow3x\left(12x+4\right)+3x\left(12x+6\right)\)

\(\Leftrightarrow3x\left[12x+4+12x+6\right]\)

\(\Leftrightarrow3x.\left(24x+10\right)\)

\(\Leftrightarrow72x^2+30x\)

Câu 2:

\(x\left(5+2x\right)+2x^2\left(x-1\right)\)

\(\Leftrightarrow5x+2x^2+2x^3-2x^2\)

\(\Leftrightarrow2x^3+5x\)

Đề 1

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72x²+39x5x+2x³5x⁵6x⁴+5x³-x²+5x