x + 121 = 300 + 120
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a: \(\left(x^3-x^2+x\right)\left(121-25y^2-10y\right)-\left(x^3-x^2+x\right)-\left(121-25y^2-10y\right)+1\)
\(=\left(x^3-x^2+x\right)\left(120-25y^2-10y\right)-\left(120-25y^2-10y\right)\)
\(=\left(120-25y^2-10y\right)\left(x^3-x^2+x-1\right)\)
\(=-\left[\left(25y^2+10y+1\right)-121\right]\left[x^2\left(x-1\right)+\left(x-1\right)\right]\)
\(=-\left(5y-10\right)\left(5y-12\right)\left(x-1\right)\left(x^2+1\right)\)
\(=-5\left(y-2\right)\left(5y-12\right)\left(x-1\right)\left(x^2+1\right)\)
b: \(x^4-14x^3+71x^2-154x+120\)
\(=x^4-5x^3-9x^3+45x^2+26x^2-130x-24x+120\)
\(=\left(x-5\right)\left(x^3-9x^2+26x-24\right)\)
\(=\left(x-5\right)\left(x^3-4x^2-5x^2+20x+6x-24\right)\)
\(=\left(x-5\right)\left(x-4\right)\left(x^2-5x+6\right)\)
\(=\left(x-5\right)\left(x-4\right)\left(x-3\right)\left(x-2\right)\)
\(\dfrac{x+27}{343}+\dfrac{x+28}{342}=\dfrac{x+121}{249}+\dfrac{x+120}{250}\)
\(\Rightarrow\left(\dfrac{x+27}{343}+1\right)+\left(\dfrac{x+28}{342}+1\right)=\left(\dfrac{x+121}{249}+1\right)+\left(\dfrac{x+120}{250}+1\right)\)
\(\Rightarrow\dfrac{x+370}{343}+\dfrac{x+370}{342}-\dfrac{x+370}{249}-\dfrac{x+370}{250}=0\)
\(\Rightarrow\left(x+370\right)\left(\dfrac{1}{343}+\dfrac{1}{342}-\dfrac{1}{249}-\dfrac{1}{250}\right)=0\)
Mà \(\dfrac{1}{343}+\dfrac{1}{342}-\dfrac{1}{249}-\dfrac{1}{250}\ne0\)
\(\Rightarrow x+370=0\Rightarrow x=-370\)
Vậy x = -370
=2x2/1x3 x 3x3/2x4x4/3x5 x ... x 11x11/10x12
=2x2x3x3x4x4x...x11x11/1x3x2x4x3x5x...x10x12
= 2x3x4x...x11)x(2x3x4x...x11)/(1x2x3x4x...x11)/(1x2x3x...x10)x(2x3x4x...x11)
=11x2/1x12
=22/12
=11/6
4/3x9/8x16/15x...x121/120=\(\dfrac{2^2}{1\cdot3}\)x\(\dfrac{3^2}{2\cdot4}\)x\(\dfrac{4^2}{3\cdot5}\)x...x\(\dfrac{11^2}{10\cdot12}\)=\(\dfrac{2}{3}\)x\(\dfrac{11}{10}\)=\(\dfrac{11}{15}\)
B=1x3/2x2x2x4/3x3x3x5/4x4x...x10x12/11x11
B=1x3x2x4x3x5x...x10x12/2x2x3x3x4x4x...x11x11
B=(1x2x3x...x10)x(2x3x5x...x12)/(2x3x4x...x11)x(2x3x4x...x11)
B=1x12/11x2
B=12/22
B=6/11
Vậy B = 6/11
\(120+x=300\)
\(x=300-120\)
\(X=180\)
Vậy \(x=180\)
chúc bn học gioi!@@
x + 121 = 300 + 120
x + 121 = 420
x = 420 - 121
x = 299
Bạn tk mình đi . Ai tk mình mình tk lại cho
X+121=300+120
X+121=420
X=420-121
X=299