chứng tỏ a. (a-b+c) - (a+c) = -b b. - (a+b-c) + (a-b-c ) =-2b c. (a+b)-(b-a)+c=2a+c d. a(b+c)-a(b+d)=a(c-d) e. a(b-c) +a(d+c) =a(b+d)

Các câu hỏi liên quan

Use the following sets of words and phrases to write a letter. Make all the changes and additions if necessary. Dear Na, I/ already/ arrive home/ New York ...................................................................................................... 2. It/ happy/ see/ whole family again. ...................................................................................................... 3. Thank/ for/ lovely time/ you/ house ...................................................................................................... 4. It/ kind/ you/ show me so much/ hometown ...................................................................................................... 5. I/ really impressed/ friendliness/ your people ...................................................................................................... 6. mountainous sights/ make/ deep impression/ me ...................................................................................................... 7. I still remember/ invited/ eat/ sour meat/ and/ it/ delicious ...................................................................................................... 8. your homeland/ beautiful/ so/ I wish/ have a chance/ visit/ again ...................................................................................................... 9. If/ you/ time/ write/ me ...................................................................................................... 10. I/ look/ hear/ you/. Give/ regards/ parents ...................................................................................................... Love, Daisy