Thực hiện phép nhân sau :
a,\(6x\left(2x-1\right)\) e,\(\left(3x-x^2+6\right)\dfrac{2}{3}x^2\)
b,\(\left(5x-3\right)\dfrac{2}{3}x\) f,\(-\dfrac{5}{6}x\left(\dfrac{2}{3}x^4+\dfrac{3}{14}x^3-\dfrac{2}{3}x^2\right)\)
c,\(-5x^3\left(3x^2-7\right)\) g,\(\left(4x-3\right)\left(x+2\right)\)
d,\(-3x\left(5x^2-2x-1\right)\) h, \(\left(5x+2\right)\left(-x^2+3x+1\right)\)
...
Đọc tiếp
Thực hiện phép nhân sau :
a,\(6x\left(2x-1\right)\) e,\(\left(3x-x^2+6\right)\dfrac{2}{3}x^2\)
b,\(\left(5x-3\right)\dfrac{2}{3}x\) f,\(-\dfrac{5}{6}x\left(\dfrac{2}{3}x^4+\dfrac{3}{14}x^3-\dfrac{2}{3}x^2\right)\)
c,\(-5x^3\left(3x^2-7\right)\) g,\(\left(4x-3\right)\left(x+2\right)\)
d,\(-3x\left(5x^2-2x-1\right)\) h, \(\left(5x+2\right)\left(-x^2+3x+1\right)\)
i, \(\left(2x^3-7x+4\right)\left(-13x^2+6x+5\right)\)
\(a)6x\left(2x-1\right)\\ =6x\cdot2x-6x\\ =12x^2-6x\\ b)\left(5x-3\right)\dfrac{2}{3}x\\ =5x\cdot\dfrac{2}{3}x-3\cdot\dfrac{2}{3}x\\ =\dfrac{10}{3}x^2-2x\\c)-5x^3\left(3x^2-7\right)\\ =-5x^3\cdot3x^2-5x^3\cdot\left(-7\right)\\ =-15x^5+35x^3\\ d)-3x\left(5x^2-2x-1\right)\\ =-3x\cdot5x^2-3x\cdot-2x-3x\cdot-1\\ =-15x^3+6x^2+3x\)
\(e)\left(3x-x^2+6\right)\dfrac{2}{3}x^2\\ =3x\cdot\dfrac{2}{3}x^2-x^2\cdot\dfrac{2}{3}x^2+6\cdot\dfrac{2}{3}x^2\\ =2x^3-\dfrac{2}{3}x^4+4x^2\\ f)-\dfrac{5}{6}x\left(\dfrac{2}{3}x^4+\dfrac{3}{14}x^3-\dfrac{2}{3}x^2\right)\\ =-\dfrac{5}{6}x\cdot\dfrac{2}{3}x^4-\dfrac{5}{6}x\cdot\dfrac{3}{14}x^3+\dfrac{2}{3}x^2\cdot\dfrac{5}{6}x\\ =-\dfrac{5}{9}x^5-\dfrac{5}{28}x^4+\dfrac{5}{9}x^3\\ g)\left(4x-3\right)\left(x+2\right)\\ =4x\left(x+2\right)-3\left(x+2\right)\\ =4x^2+8x-3x-6\\ =4x^2+5x-6\\ h)\left(5x+2\right)\left(-x^2+3x+1\right)\\ =5x\left(-x^2+3x+1\right)+2\left(-x^2+3x+1\right)\\ =-5x^3+15x^2+5x-2x^2+6x+2\\ =-5x^3+13x^2+11x+2\)