Toán Lớp 8: 2/5xy*(xy-5x+10y) 3x/x-2-12/x(x-2)-7/x

Question

Toán Lớp 8:  2/5xy*(xy-5x+10y) 3x/x-2-12/x(x-2)-7/x

lyly98 · Answer

Giải đáp:       Lời giải và giải thích chi tiết:      a)  frac{2}{5}xy(xy-5x+10y)   = frac{2}{5}x^2y^2-2x^2y+4xy^2   b)  frac{3x}{x-2}- frac{12}{x(x-2)}- frac{7}{x}   = frac{3x.x-12-7(x-2)}{x(x-2)}   = frac{3x^2-12-7x+14}{x(x-2)}   = frac{3x^2-7x+2}{x(x-2)}   = frac{3x^2-6x-x+2}{x(x-2)}   = frac{3x(x-2)-(x-2)}{x(x-2)}   = frac{(3x-1)(x-2)}{x(x-2)}   = frac{3x-1}{x}

baoquyen · Answer

Giải đáp:   $ dfrac{2}{5}xy.(xy-5x+10y)$   $=  dfrac{2}{5}xy.xy- dfrac{2}{5}xy.5x+ dfrac{2}{5}xy.10y$   $=  dfrac{2}{5}x&sup2;y&sup2;-2x&sup2;y+4$   $ dfrac{3x}{x-2}- dfrac{12}{x.(x-2)}- dfrac{7}{x}$   $=  dfrac{3x.x}{x.(x-2)}- dfrac{12}{x.(x-2)}- dfrac{7.(x-2)}{x}$   $=  dfrac{3x&sup2;-12-7x+14}{x.(x-2)}$   $=  dfrac{3x&sup2;-7x+2}{x.(x-2)}$   $=  dfrac{3x&sup2;-x-6x+2}{x.(x-2)}$   $=  dfrac{x.(3x-1)-2.(3x-1)}{x.(x-2)}$   $=  dfrac{(x-2).(3x-1)}{x.(x-2)}$   $=  dfrac{3x-1}{x}$