Bài 1: Làm tính nhân:
a) 3x(5x2 - 2x - 1) ;
b) (x2 + 2xy - 3)(-xy) ;
c) \(\dfrac{1}{2}\)x2y(2x3 - \(\dfrac{2}{5}\)xy2 - 1).
Bài 2: Rút gọn các biểu thức sau:
a) x(2x2 - 3) - x2(5x + 1) + x2 ;
b) 3x(x - 2) - 5x(1 - x) - 8(x2 - 3) ;
c) \(\dfrac{1}{2}\)x2(6x - 3) - x (x2 + \(\dfrac{1}{2}\)) + \(\dfrac{1}{2}\)(x +...
Đọc tiếp
Bài 1: Làm tính nhân:
a) 3x(5x2 - 2x - 1) ;
b) (x2 + 2xy - 3)(-xy) ;
c) \(\dfrac{1}{2}\)x2y(2x3 - \(\dfrac{2}{5}\)xy2 - 1).
Bài 2: Rút gọn các biểu thức sau:
a) x(2x2 - 3) - x2(5x + 1) + x2 ;
b) 3x(x - 2) - 5x(1 - x) - 8(x2 - 3) ;
c) \(\dfrac{1}{2}\)x2(6x - 3) - x (x2 + \(\dfrac{1}{2}\)) + \(\dfrac{1}{2}\)(x + 4).
x2y(2x3 - 
xy2 - 1); 
x(1,4x - 3,5y);
x2 - 
xy + 
y2);
Bài 1:
a,\(3x\left(5x^2-2x-1\right)\)
\(=3x.5x^2-3x.2x-3x=15x^3-6x^2-3x\)
b,\(\left(x^2+2xy-3\right)\left(-xy\right)\)
\(=x^2.\left(-xy\right)+2xy.\left(-xy\right)-3.\left(-xy\right)\)
\(=-x^3y-2x^2y^2+3xy\)
c,\(\dfrac{1}{2}x^2y\left(2x^3-\dfrac{2}{5}xy^2-1\right)\)
\(=\dfrac{1}{2}x^2y.\left(2x^3\right)-\dfrac{1}{2}x^2y.\dfrac{2}{5}xy^2-\dfrac{1}{2}x^2y\)
\(=x^5y-\dfrac{1}{5}x^3y^3-\dfrac{1}{2}x^2y\)
Chúc bạn học tốt!!!
Bài 1:
a) \(3x\left(5x^2-2x-1\right)\\ =15x^3-6x^2-3x\)
b) \(\left(x^2+2xy-3\right)\left(-xy\right)\\ =-x^3y-2x^2y+3xy\)
c) \(\dfrac{1}{2}x^2y\left(2x^3-\dfrac{2}{5}xy^2-1\right)\\ =x^5y-\dfrac{1}{5}x^3y^3-\dfrac{1}{2}x^2y\)