Toán Lớp 8: 1.thực hiện phép tính: a, x^3(2x^2+5xy-3xy^2) b, (2x-5)(3x^2+4x-2) c, (12x^3y^2-21xy+15xy^2y^2):3xy d, (5x^3-7

Question

Toán Lớp 8:  1.thực hiện phép tính: a, x^3(2x^2+5xy-3xy^2)                  b, (2x-5)(3x^2+4x-2) c, (12x^3y^2-21xy+15xy^2y^2):3xy         d, (5x^3-7x^2+9x+6):(x^2-2x+3) giúp với

haianhtu97 · Answer

Giải đáp+Lời giải và giải thích chi tiết:    a) x&sup3; (2x&sup2; + 5xy - 3xy&sup2; )   = 2x^5 + 5x^4y - 4x^4y&sup2;   b) (2x-5)(3x&sup2;+4x-2)   = 6x&sup3; + 8x&sup2; - 4x - 15x&sup2; - 20x + 10   = 6x&sup3; 7x&sup2; - 24x + 10   c) (12x&sup3;y&sup2; - 21xy+ 15xy&sup2;y&sup2;) : 3xy   = (12x&sup3;y&sup2; : 3xy) + (-21xy : 3xy) + (15xy&sup2;y&sup2; : 3xy)   = 4x&sup2;y - 7+ 5y&sup3;    d) (5x&sup3; - 7x&sup2; + 9x + 6) : ( x&sup2; - 2x + 3)

lanhuongthu · Answer

a)x^3(2x^2+5xy-3xy^2)   =2x^6+5x^4y-3x^4y^2   b)(2x-5)(3x^2+4x-2)   =6x^3+8x^2-4x-15x^2-20x+10   =6x^3-7x^2-24x+10   c)(12x&sup3;y&sup2;-21xy+15xy&sup2;y&sup2;):3xy   =4x&sup2;y-7+5y&sup3;   d)(5x&sup3;-7x&sup2;+9x+6):(x&sup2;-2x+3)   =5x+3(dư-3)