SO SANH
A= 2009 x 2011 va B= 2010^2
trinh bay day du tick cho
Bai 1.Tim x, y biet :
2x(3y-2)+(3y-2) = -55
Bai 2 .a) So sanh : -22/45 va -51/103
b) So sanh A = 2009^2009 +1 / 2009^2010 va B = 2009^2010-2/2009^2011-2
Bai 3 :
a)Tim so tu nhien co 3 chu so , biet rang khi chia so do cho cac so 25, 28,35thi duoc cac so du lan luot la 5,8,15
b)Tim x: (x+1)+(x+2)+(x+3)+...+(x+100)=205550
so sanh
a)-22/45 va -51/101
b)so sanh A=\(\frac{^{2009^{2009}}+1}{^{2009^{20010}}+1}\)va B=\(\frac{2009^{2010}-2}{2009^{2011}-2}\)
câu a ta so sánh số đối của 2 phân số này.nếu ps nào có giá trị tuyệt đối lớn hơn thì nhỏ hơn.
câu b ta nhân cả A và B với 2009 rồi so sánh 2009A với 2009B.ta được A>B
2008/2009+2009/2010+2010+2011+2011/2008
va 4
so sanh
\(\frac{2008}{2009}+\frac{2009}{2010}+\frac{2010}{2011}+\frac{2011}{2008}=1-\frac{1}{2009}+1-\frac{1}{2010}+1-\frac{1}{2011}+1+\frac{3}{2008}\)
\(=4+\left(\frac{1}{2008}-\frac{1}{2009}\right)+\left(\frac{1}{2008}-\frac{1}{2010}\right)+\left(\frac{1}{2008}-\frac{1}{2011}\right)>4\)
So sanh :2009^2009+1/2009^2010+1 va 2009^2010-2/2009^2011-2
so sanh
A=2008/2009+2009/2010+2010+2011
B=2008+2009+2010/2009+2010+2011
Dễ thấy:
\(\frac{2008}{2009}>\frac{2008}{2009+2010+2011}\)
\(\frac{2009}{2010}>\frac{2009}{2009+2010+2011}\)
\(\frac{2010}{2011}>\frac{2010}{2009+2010+2011}\)
=>\(\frac{2008}{2009}+\frac{2009}{2010}+\frac{2010}{2011}>\frac{2008}{2009+2010+2011}+\frac{2009}{2009+2010+2011}+\frac{2010}{2009+2010+2011}\)
Hay \(\frac{2008}{2009}+\frac{2009}{2010}+\frac{2010}{2011}>\frac{2008+2009+2010}{2009+2010+2011}\)
Vậy A > B
so sanh: A=2009^2009+1/2009^2010+1 và B=2009^2010-2/2009^2011-2
So sanh so A va B ma ko tinh gia tri cu the cua chung
a, A=2010×2010
B = 2009×2011
b, A=234234×233
B=233233×234
a . A = 2010 x 2010
B = 2009 x 2001
A= 2010 x 2010 = ( 2009 + 1 ) x 2010 = 2009 x 2010 + 2010
B = 2009 x 2011 = 2009 x ( 2010 + 1 ) x 2009 = 2010 x 2009 + 2009
Suy ra A > B
b . A = 234234 x 233
B = 233233 x 234
A = 234234 x 233 = 1001 x 234 x 233
A = 233233 x ( 233 + 1 ) = 233233 x 233 + 233 = 233 x 1001 x 233 + 233 = 233 x 1001 x 234
Vậy A = B
So sanh : U = \(\frac{2009^{2005}+1}{2009^{2010}+1}\)va V = \(\frac{2009^{2010}+2}{2009^{2011}+2}\)
so sanh A va B
A =\(\frac{2009}{2010}\) +\(\frac{2010}{2011}\) B =\(\frac{2009+2010}{2010+2011}\)
Ta có: \(\frac{2009}{2010}>\frac{2009}{2010+2011}\) ; \(\frac{2010}{2011}>\frac{2010}{2011+2010}\)
\(\Rightarrow\frac{2009}{2010}+\frac{2010}{2011}>\frac{2009}{2010+2011}+\frac{2010}{2011+2010}=\frac{2009+2010}{2010+2011}\)
=> A > B
Ta có \(\frac{2009}{2010}>\frac{2009}{2010+2011}\) , \(\frac{2010}{2011}>\frac{2010}{2011+2010}\)
\(\Rightarrow\frac{2009}{2010}+\frac{2010}{2011}>\frac{2009}{2010+2011}+\frac{2010}{2011+2010}=\frac{2009+2010}{2010+2011}\)
\(\Rightarrow A>B\)