so sánh :a)A=2015.2017 va B=2016^2
b)C=(2+1)(2^2+1)(2^4+1)(2^8+1)(2^16+1) va D=2^32
So sánh A và B:
a/ A=\(\left(2+1\right)\left(2^2+1\right)\left(2^4+1\right)\left(2^8+1\right)\left(2^{16}+1\right)\)
B=\(2^{32}\)
b/ A= \(2015.2017\) và B=\(2016^2\)
a) \(A=\left(2-1\right)\left(2+1\right)\left(2^2+1\right)\left(2^4+1\right)\left(2^8+1\right)\left(2^{16}+1\right)\)
\(=\left(2^2-1\right)\left(2^2+1\right)\left(2^4+1\right)\left(2^8+1\right)\left(2^{16}+1\right)\)
\(=.............................................................\)
\(=\left(2^{16}-1\right)\left(2^{16}+1\right)=2^{32}-1=B-1\)
Suy ra A < B
b) \(A=2015.2017=\left(2016-1\right)\left(2016+1\right)=2016^2-1=B-1\)
Suy ra A < B
Phần a bạn nhân thêm ở A là (2-1) là ra hằng đẳng thức, cứ thế mà triển. (Kết quả: A<B)
Phần b: phân tích A, ta có:
2015.2017= (2016-1).(2016+1)= 2016^2 -1 <2016^2
Suy ra: A<B
Trong hai số sau đây, số nào lớn hơn?
a) A = 2015.2017 và B = 20162
b) C = (2+1)(22+1)(24+1)(28+1)(216+1) và D = 232
TÌM TRƯỚC KHI HỎI
a)Ta có: \(2015=2016-1;2017=2016+1\)
\(\Rightarrow A=2015\cdot2017=\left(2016-1\right)\left(2016+1\right)=2016^2-1< 2016^2=B\)
b)Ta có:
\(C=\left(2+1\right)\left(2^2+1\right)\left(2^4+1\right)\left(2^8+1\right)\left(2^{16}+1\right)\)
\(=\left(2^2-1\right)\left(2^2+1\right)\left(2^4+1\right)\left(2^8+1\right)\left(2^{16}+1\right)\)
\(=\left(2^4-1\right)\left(2^4+1\right)\left(2^8+1\right)\left(2^{16}+1\right)\)
\(=\left(2^8-1\right)\left(2^8+1\right)\left(2^{16}+1\right)\)
\(=\left(2^{16}-1\right)\left(2^{16}+1\right)=2^{32}-1< 2^{32}=D\)
a)Ta có:A=2015.2017=(2016-1)(2016+1)=20162-1<B=20162
b)Ta có:C=(2+1)(22+1)(24+1)(28+1)(216+1)
=(2-1)(2+1)(22+1)(24+1)(28+1)(216+1)=(22-1)(22+1)(24+1)(28+1)(216+1)
=(24-1)(24+1)(28+1)(216+1)=(28-1)(28+1)(216+1)=(216-1)(216+1)=232-1
=>C<D=232
\(a,B=2016^2=\left(2017-1\right)^2=2017^2-2.2017+1=2017.\left(2017-2\right)+1=2017.2015+1>2017.2015\)Hay A<B
so sanh A va B
A= (2+1)(2^2+1)(2^4+1)(2^8+1)(2^16+1)
B=2^32
Ax(2-1)=(2-1)(2+1)(2^2+1)(2^4+1)(2^8+1)(2^16+1)=(2^2-1)(2^2+1)(2^4+1)(2^8+1)(2^16+1)=(2^4-1)(2^4+1)(2^8+1)(2^16+1)=(2^8-1)(2^8+1)(2^16+1)=(2^16-1)(2^16+1)=2^32-1
Vậy A=B
Áp dụng hằng đẵng thức A^2-B^2 đó bạn
trong hai số sau số nào lớn hơn?
a)A= 2015.2017 và B=20162
b)C=(2+1)(22+1)(24+1)(28+1)(216+1) và D = 223
Có
a) A= 2015. 2017 = ( 2016 - 1)(2016 + 1)
= 20162 - 1 < 20162 = B
=> A < B ( 20162 - 1 < 20162 )
b) C = (2+1)(22 + 1)(24 + 1)(28 + 1)(216 + 1)
= ( 2 - 1)(2+1)(22 + 1)(24 + 1)(28 + 1)(216 + 1)
= (22 - 1)(22 + 1)(24 + 1)(28 + 1)(216 + 1)
= ( 24 - 1)(24 + 1)(28 + 1)(216 + 1)
= (28 -1)(28 + 1)(216 + 1)
= ( 216 - 1)( 216 + 1)
= 232 - 1 > 223 = D
Vậy C > D ( 232 - 1 < 223 )
SO SÁNH:
a,1015+1/1016+1 va 1016+1/1017+1
b,A=1/22+1/32+1/42+...+1/1002 va B=3/4
c,A=1+1/2+...+1/100 va B=5/4
GIẢI GIÚP MÌNH NHÉ
So sánh các biểu thức
a) A= 2015 x 2017 + 2016 x 2018 và B=2016^2+2017^2 -2
b) M=(9+1).(9^2+1).(9^4+1).(9^8+1).(9^16+1).(9^32+1) và N=9^64-1
a. So sanh 2 phan so:A= 2015/2016+2016/2017+2017/2018 va B = 2015+2016+2017/2016+2017+2018
b.1/2.4+1/4.6+........+1/(2x-2).2x = 1/8
c.Cho A = 1/4+1/9+1/16+...+1/81+1/100 . Chung minh rang : A > 65/132
d.Cho B = 12/(2 . 4 ) ^ 2 + 20/ (4 . 6) ^2 + ...........+ 388/ ( 96 . 98 ) ^ 2 + 396/ ( 98 . 100 ) ^2 .Hay so sanh B voi 1 /4
So sánh A và B biết: A=(2+1)×(2^2+1)×(2^4+1)×(2^8+1)×(2^16+1)×(2^16+1) và B=2^32
Ta có: \(A=\left(2+1\right)\left(2^2+1\right)\left(2^4+1\right)\left(2^8+1\right)\left(2^{16}+1\right)\)
\(=\left(2^2-1\right)\left(2^2+1\right)\left(2^4+1\right)\left(2^8+1\right)\left(2^{16}+1\right)\)
\(=\left(2^4-1\right)\left(2^4+1\right)\left(2^8+1\right)\left(2^{16}+1\right)\)
\(=\left(2^8-1\right)\left(2^8+1\right)\left(2^{16}+1\right)\)
\(=\left(2^{16}-1\right)\left(2^{16}+1\right)\)
\(=2^{32}-1< 2^{32}\)
\(\Leftrightarrow A< B\)
so sánh các biểu thức sau
a) A= 26^2 - 24^2
B= 27^2 -25^2
b) C= (4+1)(4^2+1)(4^4+1)(a^8+1)(4^16+1)
D= 4^32 +1
a)\(A=26^2-24^2=\left(26-24\right)\left(26+24\right)=2.50\)
\(B=27^2-25^2=\left(27-25\right)\left(27+25\right)=2.52\)
Vì 52 > 50 nên B > A