Toán Lớp 8: Tính `a) (-2x^3+2x-5)x^2` `b) (-2x^3)(5x-2y^2-1)` Bài `2`: `a) 4(3x-1)-2(5-3x)= -12` `b) 2x(x-1)-3(x^2-4x)+x(x+2)= -3`

Question

Toán Lớp 8:  Tính a) (-2x^3+2x-5)x^2 b) (-2x^3)(5x-2y^2-1) Bài 2: a) 4(3x-1)-2(5-3x)= -12 b) 2x(x-1)-3(x^2-4x)+x(x+2)= -3

tuyethutanhthu · Answer

B&agrave;i 1:   a) (-2x^3+2x-5)x^2   =-2x^5+2x^3-5x^2   b) (-2x^3)(5x-2y^2-1)   =-10x^4+4x^3y^2+2x^3   B&agrave;i 2:   a) 4(3x-1)-2(5-3x)=-12   &hArr;12x-4-10+6x=-12   &hArr;18x=-12+4+10   &hArr;18x=2   &hArr;x=1/9   Vậy S={1/9}   b) 2x(x-1)-3(x^2-4x)+x(x+2)=-3   &hArr;2x^2-2x-3x^2+12x+x^2+2x=-3   &hArr;12x=-3   &hArr;x=-1/4   Vậy S={-1/4}

dananhnhu2k4 · Answer

T&iacute;nh:   $a)(-2x^{3}+2x-5)$.$x^{2}$   $=-2x^{5}-2x^{3}-5x^{2}$     $b)(-2x^{3}).(5x-2y^{2}-1)$   $=-10x^{4}+4x^{3}y^{2}+2x^{3}$   B&agrave;i 2:   $a)4.(3x-1)-2.(5-3x)=-12$   $&hArr;12x-4-10+6x=-12$   $&hArr;12x+6x=4+10-12$   $&hArr;18x=2$   $&hArr;x= frac{1}{9}$   Vậy $x= frac{1}{9}$   $b)2x.(x-1)-3.(x^{2}-4x)+x.(x+2)=-3$    $&hArr;2x^{2}-2x-3x^{2}+12x+x^{2}+2x=-3$   $&hArr;12x=-3$   $&hArr;x= frac{-1}{4} $   Vậy $x= frac{-1}{4} $   ~mk gửi ạ!!!~   ~~ ch&uacute;c tus học tốt nha!!!~~