若a+b=1,求代数式a+2a+3a+...+100a+b+2b+3b+...
问题描述：
若a+b=1,求代数式a+2a+3a+...+100a+b+2b+3b+...
答
a+2a+3a+...+100a+b+2b+3b+...100b
= (a + b) + 2(a + b) + 3(a + b).+100(a + b)
= 1 + 2 + 3 + .+ 100
= (1 + 100) × (100 ÷ 2)
= 101 × 50
= 5050再问一道吧再开一题求助吧，不用分4a-b+5a-7b+3a河滨同类项这个简单，算送你的吧4a-b+5a-7b+3a=4a + 5a + 3a - b -7b=12a - 8b