Bài 1 : Rút gọn biểu thức sau a ) xy ( x^5 – y ³ ) – x ² y ( x^4 – y ³) b ) x ³ y^4 ( x ² – y ³ ) – x ² y ³ ( x^4 – y^4) c ) 90 . 10^n – 10^n+ ² + 10

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1. $a)$

       $xy ( x^5 – y ³ ) – x ² y ( x^4 – y ³)$

   $=x^6y-xy^4-x^6y+x^2y^4$

   $=-xy^4+x^2y^4$

   $b)$

        $x ³y^4(x²-y ³)-x ²y³(x^4-y^4)$

   $=x^5y^4-x^3y^7-x^6y^3+x^2y^7$

   $c)$

       $90.10^n-10^{n+2}+10^n+1$

   $=900^n-10^{n+2}+10^n+1$

   $d)$

       $y ( x^{n-1}+ y^{n-1} ) – x^{n-1} ( x + y )$

   $=yx^{n-1}+y^n-x^n-x^{n-1}y$

   $=y^n-x^n$

   xin hay nhất ạ

   Trả lời

2. `#DyHungg`

   `a) xy(x^5-y^3)-x^2y(x^4-y^3)`

   `=x^6y-xy^4-x^6y+x^2y^4`

   `=-xy^4+x^2y^4`

    ……..

   `x^3y^4(x^2-y^3)-x^2y^3(x^4-y^4)`

   `=x^5y^4-x^3y^7-x^6y^3+x^2y^7`

   ……………….

   `90.10^n-10^(n+2)+10^(n+1)`

   `=900^n-10^(n+2)+10^(n+1)`

   ……………..

   `y(x^(n-1)+y^(n-1))-x^(n-1)(x+y)`

   `=x^(n-1)y+y^(n-1+1)-x^(n-1+1)-x^(n-1)y`

   `=y^n-x^n`

   Trả lời