Đáp án:
`45^2+40^2-15^2+80xx45`
`= (45^2-15^2)+1600+3600`
`= (45-15)xx(45+15)+1600+3600`
`= 30xx60+1600+3600`
`= 1800+1600+3600`
`= 7000`
Giải thích các bước giải:
`45^2 + 40^2 - 15^2 + 80 . 45`
`= ( 45^2 + 2 . 40 . 45 + 40^2 ) - 15^2`
`= ( 45 + 40 )^2 - 15^2`
`= 85^2 - 15^2`
`= ( 85 - 15 )( 85 + 15 )`
`= 100 . 70 = 7000`
Cho tổng A = 2006 + 2008+2010 + 2012 + x ( x ∈ N ). giá trị của x để A chia hết cho 2 là :
Giải chi tiết giúp mình với ạ. Thanks
Help mee ,TL nhanh nhất sẽ cho ctohn
Lan said that she (be) happy that day 2.my mother said that i( have to/) .. do the work myself that night 3.they say that they(see) .... then 4.he said he (not go).. the week before
1.Nam often ( play) ________________________ soccer in the afternoon. 2.My father used to (go) _____________________swimming when he was a child. 3.What about ( go) ___________________ to the zoo on Sunday evening ? 4. Tien Dung goalkeeper ( live ) ____________________ Thanh Hoa city since 1997. 5.I used to ( go) ____________________ to the zoo on Sundays when I was a child. 6.Xuan Truong footballer ( play) ________________________ soccer beautifully last Saturday. 7.Nam used to (go) _____________________fishing when he was a child. 8.They (learn ) _____________________ English for five years. 9.How about ( go) ____________________ to the zoo on Sunday evening ? 10.Quang Hai footballer ( play) ______________________ soccer beautifully last Saturday. 11.I ( meet ) ______________________ her at the movie theater last night. 12.He ( go ) ___ to the English club every Sunday. But last Sunday he ( not go ) ________ there, he went to the City’s museum. 13.Two years ago, she ( teach ) ______________________ at a village school. 14.What _____ _____you (do) ____________ yesterday morning? 15.We ( travel ) ______________________ to Hue next month. 16.My mother ( not like ) ______________________ riding a motorbike. 17.When my father was young, he (drink ) _____________________ a lot of beer. 18.Nam ( study ) ______________________ homework in the living room now. 19.Be careful ! The car ( come ) ______________________ . 20.My mother ( go ) ______________________ to the supermarket yesterday evening.
Làm đầy đủ, dễ hiểu hộ em nhé ạ.
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