Question

So sánh: (a+1).(a+2).(a+3) - a.(a+1).(a+2)  và  3.(a+1).(a+2)

Answer 1

(a + 1)(a + 2)(a + 3) - a(a + 1)(a + 2) = (a + 1)(a + 2)[(a + 3) - a] = 3(a + 1)(a + 2)

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Answer 2

Ta có: (a+1).(a+2).(a+3) - a.(a+1).(a+2)=(a+1).(a+2).(a+3-a)=(a+1).(a+2).3

=>(a+1).(a+2).(a+3) - a.(a+1).(a+2) = 3.(a+1).(a+2)