a: \(-472+\left(235-28\right)-\left(35-350\right)\)

\(=-472+235-28-35+350\)

\(=\left(-472-28\right)+\left(235-35\right)+350\)

=-500+350+200

=50

b: \(91\cdot172+91\cdot13-91\cdot85\)

\(=91\cdot\left(172+13-85\right)\)

\(=91\cdot100=9100\)

c: \(798-298:\left[19-2\left(5^2-22\right)^2\right]\cdot1^{2023}\)

\(=798-298:\left[19-2\left(25-22\right)^2\right]\)

\(=798-298:\left[19-2\cdot3^2\right]\)

\(=798-298:\left(19-18\right)\)

=798-298

=500

E cảm ơn ạ 👍

-472 + (235 - 28) - 35 - 350

= -472 + 207 - 35 - 350

= -265 - 35 - 350

= 300 - 350 = -50

-50

a: -127+208-73+92

\(=\left(-127-73\right)+\left(208+92\right)\)

\(=300-200=100\)

b: \(-46+391+246-691\)

\(=\left(-46+246\right)+\left(391-691\right)\)

\(=200-300=-100\)

c: \(-472+\left(235-28\right)-\left(35-350\right)\)

\(=-472+235-28-35+350\)

\(=\left(-472-28\right)+350+\left(235-35\right)\)

\(=-500+350+200=50\)

a) -127+208-73+92

b) 

c) 

Ta có: \(\frac{x^2+y^2}{x^2-2xy+y^2}-\frac{2}{xy}\)

\(=\frac{x^2+y^2}{\left(x-y\right)^2}-\frac{2}{xy}\)

\(=\frac{xy\left(x^2+y^2\right)-2\left(x-y\right)^2}{xy\left(x-y\right)^2}=\frac{x^3y+xy^3-2x^2+4xy-2y^2}{xy\left(x-y\right)^2}\)

TA có: \(\left(\frac{x^2+y^2}{x^2-2xy+y^2}-\frac{2}{xy}\right):\left(\frac{1}{x}-\frac{1}{y}\right)^2\)

\(=\frac{x^3y+xy^3-2x^2+4xy-2y^2}{xy\left(x-y\right)^2}:\left(\frac{y-x}{xy}\right)^2\)

\(=\frac{x^3y+xy^3-2x^2+4xy-2y^2}{xy\left(x-y\right)^2}:\frac{\left(x-y\right)^2}{x^2y^2}\)

\(=\frac{x^3y+xy^3-2x^2+4xy-2y^2}{xy\left(x-y\right)^2}\cdot\frac{x^2y^2}{\left(x-y\right)^2}=\frac{\left(x^3y+xy^3-2x^2+4xy-2y^2\right)\cdot xy}{\left(x-y\right)^4}\)

200 x 100 + 350 - 346 = 20000 + 350 - 346 = 20350 - 346 = 20005

200 x 100+350 - 346=20000+350-346=20350-346=20004

(100+235) x 2-70=335 x 2-70=670-70=600

100 x 300 x 234 x 450=30000 x 234 x 450=7020000 x 450=3159000000

Ta có: \(\frac{x^2+y^2}{x^2-2xy+y^2}-\frac{2}{xy}\)

\(=\frac{x^2+y^2}{\left(x-y\right)^2}-\frac{2}{xy}\)

\(=\frac{xy\left(x^2+y^2\right)-2\left(x-y\right)^2}{xy\left(x-y\right)^2}=\frac{x^3y+xy^3-2x^2+4xy-2y^2}{xy\left(x-y\right)^2}\)

TA có: \(\left(\frac{x^2+y^2}{x^2-2xy+y^2}-\frac{2}{xy}\right):\left(\frac{1}{x}-\frac{1}{y}\right)^2\)

\(=\frac{x^3y+xy^3-2x^2+4xy-2y^2}{xy\left(x-y\right)^2}:\left(\frac{y-x}{xy}\right)^2\)

\(=\frac{x^3y+xy^3-2x^2+4xy-2y^2}{xy\left(x-y\right)^2}:\frac{\left(x-y\right)^2}{x^2y^2}\)

\(=\frac{x^3y+xy^3-2x^2+4xy-2y^2}{xy\left(x-y\right)^2}\cdot\frac{x^2y^2}{\left(x-y\right)^2}=\frac{\left(x^3y+xy^3-2x^2+4xy-2y^2\right)\cdot xy}{\left(x-y\right)^4}\)

a: \(\frac{2x}{x^2+2xy}+\frac{y}{xy-2y^2}+\frac{4}{x^2-4y^2}\)

\(=\frac{2x}{x\left(x+2y\right)}+\frac{y}{y\left(x-2y\right)}+\frac{4}{\left(x-2y\right)\left(x+2y\right)}\)

\(=\frac{2}{x+2y}+\frac{1}{x-2y}+\frac{4}{\left(x-2y\right)\left(x+2y\right)}\)

\(=\frac{2\left(x-2y\right)+x+2y+4}{\left(x-2y\right)\left(x+2y\right)}=\frac{2x-4y+x+2y+4}{\left(x-2y\right)\left(x+2y\right)}\)

\(=\frac{3x-2y+4}{\left(x-2y\right)\left(x+2y\right)}\)

b:Sửa đề: \(\frac{x^2}{x^3-4x}+\frac{6}{6-3x}+\frac{1}{x+2}\)

\(=\frac{x^2}{x\left(x^2-4\right)}-\frac{6}{3\left(x-2\right)}+\frac{1}{x+2}\)

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

\(=\frac{2x-2-2x-4}{\left(x-2\right)\left(x+2\right)}=\frac{-6}{\left(x-2\right)\left(x+2\right)}\)

c: \(\frac{x^2+2}{x^3-1}+\frac{x}{x^2+x+1}+\frac{1}{1-x}\)

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

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

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

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

\(=\left[\left(-6x\right)+\left(x^2+9\right)\right]\left[\left(-6x\right)-\left(x^2+9\right)\right]\)

\(=\left(-6x\right)^2-\left(x^2+9\right)^2\)

\(=36x^2-\left(x^4+18x^2+81\right)\)

\(=-x^4+18x^2-81\)

\(=-\left(x^4-18x^2+81\right)\)

\(=-\left(x^2-9\right)^2\)

Ta có: \(\left(x^2-6x+9\right)\left(-x^2-6x-9\right)\)

\(=-\left(x^2-6x+9\right)\left(x^2+6x+9\right)\)

\(=-\left[\left(x-3\right)^2\cdot\left(x+3\right)^2\right]\)

\(=-\left(x^2-9\right)^2\)