Where x+y= half and xy=- half are calculated by the whole replacement method.

Expand a/b+a/c+b/a+b/c+c/b+c/a = (b+c)/a+(a+c)/b+(a+b)/c = (-a)/a+(-b)/b+(-b) The formula m3+2m2+1997 = m (m2+m-1)+m2+m-1+1998 =1998.

(a-b)+(c-a)=c-b=3, and the formula =1x1+3x3x3+2 = 30; The formula expansion a2b4+a3b6-ab2 = (ab2) 2+(ab2) 3-(ab2) = 6x6+6x6-6 = 246.

Solving Binary Linear Equations with method of substitution

① Choose a binary linear equation with simple coefficients for deformation, and use an algebraic expression containing one unknown to represent another unknown.

(2) Substitute the deformed equation into another equation, eliminate an unknown number, and get a linear equation (when substituting, be careful not to substitute into the original equation, only substitute into another equation without deformation, so as to achieve the purpose of elimination).

(3) Solve this one-dimensional linear equation and get the unknown value.

④ Substitute the obtained unknown quantity into the deformation equation in ① to obtain the value of another unknown quantity.