Question

Chứng minh rằng abcabc + ababab chia hết cho 7

Answer 1

phân tích ra rồi cộng lại sẽ đc số chia hết cho 7

Answer 2

abcabc = 100000a+10000b+1000c+100a+10b+c

ababab= 100000a+10000b+1000a+100b+10a+b

=>  (abcabc+ababab) =  100000a+10000b+1000c+100a+10b+c+ 100000a+10000b+1000a+100b+10a+b

                                =  201110a+22111b+1001c

                                = 91.(2210a+221b+11c)

                                = 7.13.(2210a+221b+11c)

=>  (abcabc+ababab) \(⋮\)7

Answer 3

abcabc = 100000a+10000b+1000c+100a+10b+c

ababab= 100000a+10000b+1000a+100b+10a+b

=>  (abcabc+ababab) =  100000a+10000b+1000c+100a+10b+c+ 100000a+10000b+1000a+100b+10a+b

=>   (abcabc+ababab)=  201110a+22111b+1001c

=> (abcabc+ababab) = 91.(2210a+221b+11c) = 7.13.(2210a+221b+11c)

=>  (abcabc+ababab) \(⋮\)7