Lời giải:

PT $\Leftrightarrow 4x^2+4x+1=3(x^2-4)+18$

$\Leftrightarrow 4x^2+4x+1=3x^2+6$

$\Leftrightarrow x^2+4x-5=0$

$\Leftrightarrow (x-1)(x+5)=0$

$\Leftrightarrow x-1=0$ hoặc $x+5=0$

$\Leftrightarrow x=1$ hoặc $x=-5$

\(\left(2x+1\right)^2=3\left(x-2\right)\left(x+2\right)+18\)

\(\Leftrightarrow4x^2+4x+1=3\left(x^2-4\right)+18\)

\(\Leftrightarrow4x^2+4x+1=3x^2-12+18\)

\(\Leftrightarrow4x^2+4x+1=3x^2+6\)

\(\Leftrightarrow4x^2-3x^2+4x=6-1\)

\(\Leftrightarrow x^2+4x=5\)

\(\Leftrightarrow x^2+4x-5=0\)

\(\Leftrightarrow x^2+5x-x-5=0\)

\(\Leftrightarrow x\left(x+5\right)-\left(x+5\right)=0\)

\(\Leftrightarrow\left(x+5\right)\left(x-1\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x=-5\\x=1\end{matrix}\right.\)

Vậy: \(S=\left\{-5;1\right\}\)

a)25* x- x=14040:45

25x-x=312

24x=312

x=312:24

x=13

b)x*2=15-x*3

2x=15-3x

2x+3x=15

5x=15

x=15:5

x=3

a)25* x- x=14040:45

25x - x=312

24x = 312

  x=312:24

  x=13

b)x*2=15-x*3

2x=15-3x

2x+3x=15

5x=15

x=15:5

x=3

15×X=225-45=180=>X=12

A) X bằng 12.

B)X bằng 98.

Tk nha bạn và học tốt.

= 5/2 nhé

\(\frac{45}{30}\div\frac{15}{25}\)

\(=\frac{3}{2}\div\frac{3}{5}\)

\(=\frac{3}{2}\times\frac{5}{3}\)

\(=\frac{3\times5}{2\times3}=\frac{5}{2}\)

25:30 

Bằng bao nhiêu 

\(A=\frac{x^3-3x^2-7x-15}{x^5-x^4-10x^3-38x^2-51x-45}\)

\(=\frac{x^2\left(x-5\right)+2x\left(x-5\right)+3\left(x-5\right)}{x^4\left(x-5\right)+4x^3\left(x-5\right)+10x^2\left(x-5\right)+12x\left(x-5\right)+9\left(x-5\right)}\)

\(=\frac{\left(x-5\right)\left(x^2+2x+3\right)}{\left(x-5\right)\left(x^4+4x^3+10x^2+12x+9\right)}\)

\(=\frac{x^2+2x+3}{x^4+4x^3+10x^2+12x+9}\)

\(=\frac{x^2+2x+3}{\left(x^2\right)^2+2.x^2.2x+\left(2x\right)^2+6x^2+12x+9}\)

\(=\frac{x^2+2x+3}{\left(x^2+2x\right)^2+2.\left(x^2+2x\right).3+3^2}\)

\(=\frac{\left(x^2+2x+3\right)}{\left(x^2+2x+3\right)^2}=\frac{1}{x^2+2x+3}\)

b, \(A=\frac{1}{x^2+2x+3}=\frac{1}{\left(x+1\right)^2+2}\le\frac{1}{2}\forall x\)

Dấu "=" xảy ra khi: \(x+1=0\Rightarrow x=-1\)

Vậy GTLN của A là \(\frac{1}{2}\) khi x = -1

-1410

tick mk nha

=47.(-30)=-1410

Tích đi nha !

-1410

a) x - 15 = 7 + (-2)

x-15 = 5

x=20

b) | x - 5 | = 15 + (-8)

I x - 5 I = 7

1) x-5 = 7 => x = 12

2) x-5 = -7 => x= -2

Vậy x=12 hoặc x=-2

c) I x | -  25 = 45 + (-15) 

 I x | -  25 = 30

I xI = 55

Vậy x= 55 hoặc x=-55

a) x - 15 = 7 + ( - 2 )

x - 15 = 5

      x  = 5 + 15

      x  = 20

b) | x - 5 | = 15 + ( - 8 )

| x - 5 | = 7

=> x = 7 + 5 

     x = 12

c) | x | - 25 = 45 + ( - 15 )

| x | - 25 = 30

=> | x | = 30 + 25

     | x | = 55

=> x = 55

phần cuối x = - 55 hoặc 55

Mình viết thiếu

Xin lỗi nha

\(\frac{3^6.45^4-15^{13}.9^{-9}}{27^4.25^3+45^6}=\frac{3^6.\left(3.3.5\right)^4-\left(3.5\right)^{13}-\left(3^2\right)^{-9}}{\left(3^3\right)^4.\left(5^2\right)^3+\left(3.15\right)^6}=\frac{3^6.3^4.3^4.5^4-3^{13}.5^{13}-3^{-18}}{3^{12}.5^6+3^6.15^6}=\frac{3^{14}.5^4-3^{13}.5^{13}-3^{-18}}{3^{12}.5^6+3^6.\left(3.5\right)^6}=\frac{ }{ }\)

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