Tính:
\(2\dfrac{1}{547}\cdot\dfrac{3}{211}-\dfrac{546}{547}\cdot\dfrac{1}{211}-\dfrac{4}{547\cdot211}\)
2\(\dfrac{1}{547}.\dfrac{3}{211}-\dfrac{546}{547}.\dfrac{1}{211}-\dfrac{4}{547.211}\)
gọi 1/547=a, 1/211=b ta đc:
\(2a.3b-546a.b-4ab< =>6ab-546ab-4ab=-544ab=\dfrac{-544}{547.211}\)
Tính giá trị của các biểu thức sau
a) M= \(2\frac{1}{315}\cdot\frac{1}{651}-\frac{1}{105}\cdot3\frac{650}{651}-\frac{4}{315\cdot651}+\frac{4}{105}\)
b) N= \(2\frac{1}{547}\cdot\frac{3}{211}-\frac{546}{547}\cdot\frac{1}{211}-\frac{4}{547\cdot211}\)
a: \(M=\dfrac{631}{315}\cdot\dfrac{1}{651}-\dfrac{1}{105}\cdot\dfrac{2603}{651}-\dfrac{4}{315\cdot651}+\dfrac{4}{105}\)
\(=\dfrac{1}{315\cdot651}\cdot\left(631-4\right)-\dfrac{1}{105}\left(\dfrac{2603}{651}-4\right)\)
\(=\dfrac{1}{105}\cdot\dfrac{1}{1953}\cdot627+\dfrac{1}{105\cdot651}\)
\(=\dfrac{1}{105\cdot651}\left(\dfrac{1}{3}\cdot627+1\right)=\dfrac{1}{105\cdot651}\cdot210=\dfrac{2}{651}\)
b: \(N=\dfrac{1095}{547}\cdot\dfrac{3}{211}-\dfrac{546}{547\cdot211}-\dfrac{4}{547\cdot211}\)
\(=\dfrac{1}{547\cdot211}\left(1095\cdot3-546-4\right)\)
\(=\dfrac{1}{547\cdot211}\cdot2735=\dfrac{5}{211}\)
Tính giá trị của biểu thức:
a)\(2\dfrac{1}{547}\).\(\dfrac{3}{211}\)-\(\dfrac{546}{547}\).\(\dfrac{1}{211}\)-\(\dfrac{4}{547.211}\)
b)x15-8x14+8x13-8x12+...-8x2+8x-5 với x=7
c)\(2\dfrac{1}{315}\).\(\dfrac{1}{651}\)-\(\dfrac{1}{105}\).\(3\dfrac{650}{651}\)-\(\dfrac{4}{315.651}\)+\(\dfrac{4}{105}\)
a: \(=\dfrac{\left(2\cdot547+1\right)\cdot3}{547\cdot211}-\dfrac{546}{547\cdot211}-\dfrac{4}{547\cdot211}\)
\(=\dfrac{2735}{547\cdot211}=\dfrac{5}{211}\)
b: x=7 nên x+1=8
\(x^{15}-8x^{14}+8x^{13}-8x^{12}+...-8x^2+8x-5\)
\(=x^{15}-x^{14}\left(x+1\right)+x^{13}\left(x+1\right)-x^{12}\left(x+1\right)+...-x^2\left(x+1\right)+x\left(x+1\right)-5\)
\(=x^{15}-x^{15}-x^{14}+x^{14}-...-x^3-x^2+x^2+x-5\)
=x-5=7-5=2
Tính giá trị của biểu thức ;
A=2/1/547 x 3/211 - 546/547 x 1/211 - 4/547x211
\(2\frac{1}{547}.\frac{3}{211}-\frac{546}{547}.\frac{1}{211}-\frac{4}{547.211}\)
Tính nhanh
Tính: \(B=2\frac{1}{547}.\frac{3}{211}-\frac{546}{547}.\frac{1}{211}-\frac{4}{547.211}\)
=>\(B=\left(2\cdot\frac{1}{547}\cdot\frac{3}{211}\right)-\left(\frac{546}{547}\cdot\frac{1}{211}\right)-\left(\frac{4}{547\cdot211}\right)\)
=>\(B=\frac{6}{547\cdot211}-\frac{546}{547\cdot211}-\frac{4}{547\cdot211}\)
=>\(B=\frac{6}{115417}-\frac{546}{115417}-\frac{4}{115417}\)
=>\(B=\frac{-544}{115417}\)
M = \(2.\frac{1}{547}.\frac{3}{211}-\frac{546}{547}.\frac{1}{211}-\frac{4}{547.211}\)=?
M = \(2.\frac{1}{547}.\frac{3}{211}-\frac{546}{547}.\frac{1}{211}-\frac{1}{247.211}\)
M = \(\frac{6}{547.211}-\frac{546}{547.211}-\frac{4}{547.211}\)
M = \(\frac{-544}{547.211}\)
\(M=2.\frac{1}{547}.\frac{3}{211}-\frac{546}{547}.\frac{1}{211}-\frac{4}{547.211}\)
\(M=\left(2.\frac{1}{547}.\frac{3}{211}\right)-\left(\frac{546}{547}.\frac{1}{211}\right)-\left(\frac{4}{547.211}\right)\)
\(M=\frac{6}{547.211}-\frac{546}{547.211}-\frac{4}{547.211}\)
\(M=\frac{6}{115417}-\frac{546}{115417}-\frac{4}{115417}\)
\(M=\frac{-540}{115417}-\frac{4}{115417}\)
\(M=\frac{-544}{115417}\)
Tính P= 2 và 1/547. 3/222-546/547.1/211-4/547.211
Bài 1: Tính hợp lý. (nếu có thể)
A= 1/10+1/40+1/88+1/154+1/238+1/340
B=2 +1/547 . 3/211 - 546/547 - 4/547.211
D= 1/3+1/6+1/12+1/24+1/48
E= 1/2 - 1/4 + 1/8 - 1/16 +...+ 1/2048
F= 0,5 - 1/3 - 0,4 -5/7 - 1/6 + 4/35 - 1/41
Giải:
A=1/10+1/40+1/88+1/154+1/238+1/340
A=1/2.5+1/5.8+1/8.11+1/11.14+1/14.17+1/17.20
A=1/2-1/5+1/5-1/8+1/8-1/11+1/11-1/14+1/14-1/17+1/17-1/20
A=1/2-1/20
A=9/20
D=1/3+1/6+1/12+1/24+1/48
D=1/3+1/2.3+1/3.4+1/4.6+1/6.8
D=1/3+1/2-1/3+1/3-1/4+1/2.(2/4.6+2/6.8)
D=1/3+1/2-1/4+1/2.(1/4-1/6+1/6-1/8)
D=1/3+1/4+1/2.(1/4-1/8)
D=1/3+1/4+1/2.1/8
D=1/3+1/4+1/16
D=31/48
F=0,5-1/3-0,4-4/7-1/6+4/35-1/41
F=1/2-1/3-2/5-4/7-1/6+4/35-1/41
F=1/6-(-6/35)-1/6+4/35-1/41
F=(1/6-1/6)+(6/35+4/35)-1/41
F=0+2/7-1/41
F=2/7+1/41
F=75/287
Chúc bạn học tốt!