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\(E=\frac{x^3+3x^2-4}{x^3-3x+2}\)
\(=\frac{x^3+2x^2+x^2-4}{x^3-4x+x+2}\)
\(=\frac{x^2.\left(x+2\right)+\left(x-2\right)\left(x+2\right)}{x.\left(x^2-4\right)+\left(x+2\right)}\)
\(=\frac{\left(x+2\right)\left(x^2+x-2\right)}{x.\left(x-2\right)\left(x+2\right)+\left(x+2\right)}\)
\(=\frac{\left(x+2\right)\left(x^2-x+2x-2\right)}{\left(x+2\right)\left[x.\left(x-2\right)+1\right]}\)
\(\frac{\left(x+2\right)\left[x.\left(x-1\right)+2.\left(x-1\right)\right]}{\left(x+2\right)\left(x^2-2x+1\right)}\)
\(=\frac{\left(x+2\right)\left(x-1\right)\left(x+2\right)}{\left(x+2\right)\left(x-1\right)^2}=\frac{x+2}{x-1}\)
Đề :
https://dehocsinhgioi.com /de-thi-hoc-sinh-gioi-toan-8-bac-ninh-2019/
https://dehocsinhgioi.com/de-thi-tuyen-chon-hoc-sinh-gioi-toan-8-de-kho-nha/
https://dehocsinhgioi.com/de-thi-hoc-sinh-gioi-toan-8-nam-2019/
https://dehocsinhgioi.com/de-thi-hoc-sinh-gioi-toan-9-phong-gddt-hai-duong-2014-2015/
https://dehocsinhgioi.com/de-thi-hoc-sinh-gioi-toan-8-bac-ninh-2019/
mk ko up hình đc nên bạn tham khảo nha!
\(\left(x^2+5x\right)^2+10x^2+50x+24\)
\(=\left(x^2+5x\right)^2+10\left(x^2+5x\right)+24\)
\(=\left(x^2+5x\right)^2+4\left(x^2+5x\right)+6\left(x^2+5x\right)+24\)
\(=\left(x^2+5x\right)\left(x^2+5x+4\right)+6\left(x^2+5x+4\right)\)
\(=\left(x^2+5x+4\right)\left(x^2+5x+6\right)\)
\(=\left[x^2+x+4x+4\right]\left[x^2+2x+3x+6\right]\)
\(=\left[x\left(x+1\right)+4\left(x+1\right)\right]\left[x\left(x+2\right)+3\left(x+2\right)\right]\)
\(=\left(x+1\right)\left(x+4\right)\left(x+2\right)\left(x+3\right)\)
Chúc bạn học tốt.
(x2 + 5x)2 + 10x2 + 50x + 24
= ( x2 + 5x)2 + 10 ( x2 + 5x) + 24 (1)
Đặt t = x2 + 5x
(1) <=> t2 + 10t + 24
= t2 + 2. t . 5 + 25 -1
= ( t + 5 )2 -1
= ( t + 5 -1 ) ( t + 5 + 1)
= ( t + 4 ) ( t + 6)
thay t = x2 + 5x vào bt trên, ta có
( x2 + 5x + 4) ( x2 + 5x + 6 )
= ( x2 + x + 4x + 4 ) ( x2 + 2x + 3x + 6)
= ( x + 1 ) ( x + 4 ) ( x + 2 ) ( x + 3)
Phúc Nguyên : chắc không