Cau1.Hay tinh hop li cac tong sau day
a) A=1/3+1/3^2+1/3^3+....+1/3^100
b)B=10/56+10/140+10/260+....+10/1400
Cau2
Cho C=2+2^2+2+3+...+2^99+2^100
a)Tinh tong C
b)Tim x de2^2x-1-2=C
c)Chung minh rang C chia het ch 31
Cau 3
a) So sanh: A=2005^2005+1/2005^2006+1 va B=2005^2004+1/2005^2005+1
b)Tim so nguyen m sao cho so m+6/m-1 la so nguyen
Cau4
Cho AB=x(cm) AC=7(cm) BC=2x-1(cm) .Timx sao cho ba diem A B C thang hang
Cau 5
a) Tim x,y thuoc N biet 2^x+624=5^y
b)Voi gia tri nao cua x ,y thi bieu thuc A=/x-y/+/x+1/+2013 dat gia tri nho nhat .Tim gia tri nho nhat do
Chu y dau ''/'' la dau gia tri tuyet doi
Cau 6
De chuan bi cho ki thi hoc sinh gioi, mot hoc sinh giai 35 bai toan.Biet rang cu moi bai dat loai gioi duoc thuong 20 diem moi bai dat loai kha trung binh duoc thuong 5 diem . Con moi bai yeu, kem bi tru 10. Lam xong 35 bai em do duoc thuong 130 diem .Hoi co bao nhieu bai loai gioi ,bao nhieu bai loaiyeu ,kem .Biet rang co8 bai kha va trung binh
Ai lam dung minh tich cho
Nho giai ra nha
1.tinh
C=(1+1/1.3)(1+1/2.4)(1+1/3.5)...(1+1/2014.2016)
2.tim x
a,5^x=125
b,3^2.x=81
c,5^2.x-3-2=10
d,(5^x-1).3-2=10
3.tim n de n^2+2016 la 1 so chinh phuong
Giai nhanh giup minh nhung phai co phep tinh ,loi giai duong hoang nhe!!!!!
Viet x mu 10 duoi dang
a tich cua 2 luy thua trong do so bi chia la x mu 7
b luy thua cua x mu 2
c thuong cua 2 luy thua trong doso bi chia la x mu 12
1)viet cac bieu thuc sau duoi dang mot luy thua bang nhieu cach neu co
a)410.815
b)82.253
c)(2a3x2y).(8a2x3y4).(16a3x3y3)
cac ban giup minh nha !!
a) Tinh : 102;103;104;105
b) Viet moi so sau duoi dan luy thua cua 0:
1 000; 1 000 000; 1 ti ;1 000...0 ( 12 chu so 0 )
1, tinh cac gia tri cac bieu thuc sau mot cach hop li;
a,27+73-30:(25-10)
133.(33+20)-33.(133+20)
(15^2015+15^2016):15^2015
2,tim so nguyen x biet
2x-4=-18
(x+1)^3=27
13-(x-2)=11
3,nguoi ta to chuc phat qua cho cac em nho nhan dip tet trung thu gom co 133goibanh,80goi keo,170hop mut duoc chia deu vao cac phan qua.nhung khi chia thi thi con thua 13 goi banh ,8goi keo va 2 hop mut khong chia duoc cac phan qua.hoi nguoi ta da phat qua duoc nhieu nhat bao nhieu ban nho
4,tren tia ax,ve cac diem b,c sao cho ac=4,ab=8.
a,hoi trong 3 diem a,b,c diem nao nam giua 2diem con lai .
b,diem c co phai la trung diem cua doan thang ab khong . vi sao
5, tinh tong a=6+18+36+60+.........+29700+30300
mong cac ban se giup minh nhe ban nao giup minh se like cho nhieu cai va nho co loi giai phep tinh dang hoang nha i love you
.
Bai 1: a)Tim so tu nhien a biet 1960va2002 chia cho a cung co so du la 28
b)Tim 2 sop tu nhien a va b , biet :BCNN(a,b)=300;UCLN(a,b)=15 va a+15=b
Bai 2:a)Tong sau la binh phuong so nao ?
S=1+3+5+7+...+199
b) Cho so ab va so ababab
1)chung to ababab la boi cua ab
2)So 3 va 10101 co phai la uoc cua ababab khong , vi sao?
Bai 3
a)Hay viet them dang sau so 664 ba chu so de nhan duoc sdo co 6 chu so chia het cho 5,9,11
b)Tim so nguyen x thuoc Z biet rang :
(x^2-1)(x^2-4)<0
Bai 4 :tim so nguyen x va y biet: xy-x+2y=3
Cho A=3+3^2+3^3+3^4+...+3^100
a, tinh gia tri cua A
b, Chung to A chia het cho 10
c, tim so du cua A khi chia cho 13
d, tim x 2A-3=3^x+100
e, 2A co phai la so chinh phuong khong
dag can gap
113.(tr99,ko hieu dc trong sach nha)
5 | ||
4 | 0 |
Hay dien cac so 1,-1,2,-2,3,-3,vao cac o trong o hinh vuong ben(moi so vao 1 o ) sao cho tong 3 so tren moi dong,moi cot hoac moi duong cheo deu bang nhau
114.Liet ke va tinh tong tat ca cac so nguyen x thoa man:
a) -8 < x < 8 b) -6 < x < 4 c) -20 < x < 21
118.Tim so nguyen x biet :
a) 2x - 35 = 15 ; b) 3x + 17 = 2; c) | x - 1 | = 0
119. Tinh bang 2 cach:
a) 15 x 12 - 3 x 5 x 10 b) 45 - 9 x ( 13 + 5 ) c) 29 x ( 19 - 13 ) - 19 x ( 29 - 13 )
120. Cho 2 tap hop : A = { 3;-5;7} ; B = { -2;4;-6;8}
a) Co bao nhieu tich ab ( voi a thuoc A va b thuoc B ) duoc tao thanh?
b) Co bao nhieu tich lon hon 0,bao nhieu tich nho hon 0?
c) Co bao nhieu tich la boi cua 6?
d) Co bao nhieu tich la uoc cua 20?
Giup mk nha may bn dang can gap