化简求值:〔3(ab-1)^2-(2ab+3)(1-ab)〕/2分之5ab,其中a= -1,b=2分之1.
參考答案:解:<提示:^指2>
〔3(ab-1)^2-(2ab+3)(1-ab)〕/2分之5ab
=[3(a^b^-2ab+1)-(2ab-2a^b^+3-3ab)]/2分之5ab
=[3ab^-6ab+3-2ab+2a^b^-3+3ab]/2分之5ab
=[5a^b^-5ab]*5ab分之2
=5a^b^*5ab分之2-5ab*5ab分之2
=2ab-2
当a= -1,b=2分之1时,
2ab-2=2*(-1)*2分之1-2=-1-2=-3