Toán Lớp 8: thực hiện phép tính a, x^2-2/x^2-4x + 3x/x-4 + 7/5x b, 6/x^2-3x+2 + 2x-2/x^2-4

Question

Toán Lớp 8:  thực hiện phép tính a, x^2-2/x^2-4x + 3x/x-4 + 7/5x b, 6/x^2-3x+2 + 2x-2/x^2-4

kymmailien · Answer

#AkaShi   a) (x^2-2)/(x^2-4x)+3/(x-4)+7/(5x)   ( Đk: x  ne  4 ; x  ne 0 )   =(x^2-2)/(x(x-4))+3/(x-4)+7/(5x)   =(5(x^2-2))/(5x(x-4))+(15x)/(5x(x-4))+(7(x-4))/(5x(x-4))   =(5x^2-10+15x+7x-28)/(5x(x-4))   =(5x^2+22x-38)/(5x(x-4))   ........................   6/(x^2-3x+2)+(2x-2)/(x^2-4)   =6/(x^2-x-2x+2)+(2x-2)/(x^2-4)   =6/((x-1)(x-2))+(2x-2)/((x-2)(x+2))   =(6(x+2))/((x-1)(x-2)(x+2))+((2x-2)(x-2))/((x-2)(x+2)(x-1))   =(6x+12+2x^2-6x-4)/((x-2)(x+2)(x-1))   =(2x^2+8)/((x-2)(x+2)(x-1))

mytamhoang · Answer

a,5(x&sup2;-2)/5x(x-4)+15x&sup2;/5x(x-4)+ 7(x-4)/5x(x-4)   =5x&sup2;-10+15x&sup2;+7x-28/5x(x-4)   =20x&sup2;+7x-38/5x(x-4)   b,6/x&sup2;-2x-x+2 +2x-2/(x-2)(x+2)   =6/x(x-2)-(x-2) +2(x-1)/(x-2)(x+2)   =6(x+2)/(x-1)(x+2)(x-2) +2(x-1)&sup2;/(x-1)(x-2)(x+2)   =6x+12+2x&sup2;-4x+2/(x-1)(x-2)(x+2)   =2x&sup2;+2x+14/(x-1)(x-2)(x+2)