15+15+15=?
102+102=?
1=15^4+15^8+...+15^96+15^100/1+15^2+15^4+...+15^98+15^100+15^102
\(\frac{1+15^4+15^8+...+15^{96}+15^{100}}{1+\frac{15}{2}+\frac{15}{4}+...+\frac{15}{100}+\frac{15}{102}}\)
1+15^4+15^8+...+15^96+...+15^100
1+15^4+15^8+...+15^96+15^100+15^102
giúp mình nha mình cick cho -_-
Bai 1
đặt A = 1 + 15^4 + 15^8 + .... + 15^100
=> 15^4A = 15^4 + 15^8 + 15^12 + .... + 15^104
ta có
15^4A = 15^4 + 15^8 + 15^12 + .... + 15^100 + 15^104
-
A = 15^4 + 15^8 + 15^12 + .... + 15^100 + 1
50624A = 15^104 - 1
=> A = (15^104-1)/50624
bài 2 làm tương tự cũng đặt A và nhân A với 15^4 (bạn thông cảm mình không có nhiều thời gian)
Tìm x , biết:
a) (102−15)−(15−x)=6
b) −154+(x−9−18)=40
a) (102 − 15) − (15 − x) = 6
102 − 15 − 15 + x = 6
x = 6 − 102 + 15 + 15
x = −66.
b) −154 + (x − 9 − 18) = 40
−154 + x − 9 – 18 = 40
x = 40 + 154 + 9 + 18
x = 221.
a, (102-15)-(15-x)=6
87 - (15-x)=6
(15-x)=87-6
15-x = 81
x = 15-81
x = -66
b,-154+(x-9-18)=40
(x-9-18)=40-(-154)
x-9-18 =194
x-9 =194+18
x-9 = 212
x = 212+9
x = 221
Rút gọn:
B=\(\dfrac{1+15^4+15^8+...+15^{96}+15^{100}}{1+15^2+15^4+...+15^{98}+15^{100}+15^{102}}\)
B=\(\dfrac{1+15^4+15^8+...+15^{96}+15^{100}}{\left(1+15^4+15^8+..+15^{96}+15^{100}\right)+\left(15^2+15^6+...+15^{98}+15^{102}\right)}\)
=\(\dfrac{1+15^4+15^8+...+15^{96}+15^{100}}{\left(1+15^4+15^8+...+15^{96}+15^{100}\right)+15^2.\left(1+15^{14}+15^8+...+15^{96}+15^{100}\right)}\)
\(\dfrac{\left(1+15^4+15^8+...+15^{96}+15^{100}\right)}{\left(1+15^4+15^8+...+15^{96}+15^{100}\right)\left(1+15^2\right)}\)
=\(\dfrac{1}{1+15^2}=\dfrac{1}{226}\)
B=\(\frac{1+15^4+15^8+...+15^{96}+15^{100}}{1+15^2+15^4+...+15^{98}+15^{100}+15^{102}}\)
Tính B
llllllllllllllllllllllllllllllllllllllllllll
Tính:
15 / 90 . 94 + 15 / 94 . 98 + 15 / 98 .102+...+ 15 / 146.150
10 / 56 + 10/ 140 + 10 / 260+...+ 10 /1400
=15.(1/90.94+1/94.98+....+1/146.150) =15.1/4(1/90-1/94+1/94-1/98+1/9 --......+1/150 =15/4.(1/90 - 1/150) =15/4.1/1225 =1/60 NHỚ nhấn đúng nha
Rút gọn:
\(B=\frac{1+15^4+15^8+...+15^{96}+15^{100}}{\left(1+15^4+15^8+...+15^{96}+15^{100}\right)+\left(15^2+15^6+...+15^{98}+15^{102}\right)}\)
1/ thực hiện phép tính
C)c=[(1/18-3/162)×81/17+35/34]:(9/15+7/102)×102/5+2017
\(=\left[\dfrac{9-3}{162}\cdot\dfrac{81}{17}+\dfrac{35}{34}\right]:\left(\dfrac{3}{5}+\dfrac{7}{102}\right)\cdot\dfrac{102}{5}+2017\)
\(=\left[\dfrac{6}{2}\cdot\dfrac{1}{17}+\dfrac{35}{34}\right]:\dfrac{341}{510}\cdot\dfrac{102}{5}+2017\)
\(=\dfrac{41}{34}\cdot\dfrac{510}{341}\cdot\dfrac{102}{5}+2017=\dfrac{12546}{341}+2017=\dfrac{700343}{341}\)