Question

先化簡下式，再取一個(gè)你喜歡的數(shù)代入求值：7a-2[3a²+(2+3a-a²)]

Answer 1

解：原式=7a-2[3a²+2+3a-a²]
              =7a-6a²-4-6a+2a²
              =(-6+2)a²+(7-6)a-4
              =-4a²+a-4
當(dāng)a=1時(shí)，原式=-4×1+1-4
                       =-7