4(3x-4)-2=18
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\(4\left(3x-4\right)-2=18\\ 4\left(3x-4\right)=20\\ 3x-4=5\\ 3x=9\\ x=3\)
Vậy.........
a: \(\Leftrightarrow x^2\left(9x^2-4\right)=0\)
\(\Leftrightarrow x^2\left(3x-2\right)\left(3x+2\right)=0\)
hay \(x\in\left\{0;\dfrac{2}{3};-\dfrac{2}{3}\right\}\)
b: \(\Leftrightarrow2x^4-4x^2+3x^2-6=0\)
\(\Leftrightarrow x^2-2=0\)
hay \(x\in\left\{\sqrt{2};-\sqrt{2}\right\}\)
d: \(\Leftrightarrow x^4-9x^2+6x^2-54=0\)
\(\Leftrightarrow x^2-9=0\)
=>x=3 hoặc x=-3
1) \(\left(x+1\right)\left(x+2\right)-3x\left(x-4\right)=x^2+3x+2-3x^2+12x=-2x^2+15x+2\)
2) \(\left(3x-4\right)\left(x-2\right)=3x\left(x-9\right)\)
\(\Leftrightarrow3x^2-10x+8=3x^2-27x\)
\(\Leftrightarrow17x=-8\Leftrightarrow x=-\dfrac{8}{17}\)
3) \(-3\left(x-4\right)\left(x-2\right)-x^2\left(-3x+18\right)+24x-25\)
\(=-3x^3+6x^2+12x^2-24x+3x^3-18x^2+24x-25=-25\)
4(3x-4)-2=18
=> 4(3x-4)=18+2
=> 3x-4=20:4
=> 3x=5+4
=> x=9:3
=> x=3
12x - 16 - 2 = 18
12x = 18 + 16 + 2
12x = 36
x = 36 : 12
x = 3
Chúc bạn học giỏi ^^ :(
4 ( 3x - 4 ) - 2 = 18
4 ( 3x - 4 ) = 18 + 2
4 ( 3x - 4 ) = 20
( 3x - 4 ) = 20 : 4
( 3x - 4 ) = 5
3x = 5 + 4
3x = 9
x = 9 : 3
x = 3
Ta có: \(C=-3x\left(x-4\right)\left(x-2\right)+x\left(3x-18\right)-25\)
\(=-3x\left(x^2-6x+8\right)+3x^2-18x-25\)
\(=-3x^3+18x^2-24x+3x^2-18x-25\)
\(=-3x^3+21x^2-42x-25\)
\(\left(4x+1\right)\left(12x-1\right)\left(3x-2\right)\left(x+1\right)-4\) (Sửa đề)
\(=[\left(4x+1\right)\left(3x+2\right)][\left(12x-1\right)\left(x+1\right)]-4\)
\(=\left(12x^2+11x+2\right)\left(12x^2+11x-1\right)-4\)
Đặt \(12x^2+11x-1=n\)
\(=\left(n+3\right)n-4\)
\(=n^2+3n-4\)
\(=n^2-n+4n-4\)
\(=n\left(n-1\right)+4\left(n-1\right)\)
\(=\left(n-1\right)\left(n+4\right)\)
\(=\left(12x^2+11x-1-1\right)\left(12x^2+11x-1+4\right)\)
\(=\left(12x^2+11x-2\right)\left(12x^2+11x+3\right)\)
\(\left(3x+4\right)\left(x+1\right)\left(6x+7\right)^2=6\)
\(\Leftrightarrow\left(3x^2+7x+4\right)\left(36x^2+84x+49\right)=6\)(1)
Đặt \(\left(3x^2+7x+4\right)=n\)lúc đó (1):
\(\left(12n+1\right)n=6\)
\(\Rightarrow\hept{\begin{cases}n=0,75\\n=\frac{2}{3}\end{cases}}\)
\(\Rightarrow\hept{\begin{cases}x=\frac{-2}{3}\\x=\frac{-5}{3}\end{cases}}\)
a) \(\Rightarrow72-20x-36x+84=30x-240-6x-84\)
\(\Rightarrow80x=480\Rightarrow x=6\)
b) \(\Rightarrow15x+25-8x+12=5x+6x+36+1\)
\(\Rightarrow4x=0\Rightarrow x=0\)
c) \(\Rightarrow10x-16-12x+15=12x-16+11\)
\(\Rightarrow14x=4\Rightarrow x=\dfrac{2}{7}\)
4(3x-4)-2=18
4(3x-4)=20
=> 3x-4 =5
=>3x=9
=>x=3
4.(3x-4)-2=18
4.(3x-4) =18+2
4.(3x-4) =20
3x-4 =20:4
3x-4 = 5
3x =5+4
3x =9
x =9:3
x =3