A=(x-1)-7
Tìm x:
a) x - 4/5 = ( 4/7 + 1/7 ) x 7/5 b) x - 1/5 = 7/5 x 1/4 + 8/5 x 1/4
Câu 1: Tập hợp A các số tự nhiên nhỏ hơn 7 được viết là:
A. A = {x ∈ N* | x < 7}
B. A = {x ∈ N | x < 7}
C. A = {x ∈ N* | x ≤ 7}
D. A = {x ∈ N | x > 7}
tính
a=(1+(7/9))x(1+(7/20))x(1+(7/33))x...........x(1+(1/2900))
find the value of x such that (Tìm x biết ) : \(\frac{x+7}{\left(a+1\right)\left(a+7\right)}=\frac{1}{a+1}-\frac{1}{a+7}\)
( a khác -1; -7 )
\(\frac{1}{a+1}-\frac{1}{a+7}=\frac{a+7}{\left(a+1\right)\left(a+7\right)}-\frac{a+1}{\left(a+1\right)\left(a+7\right)}=\frac{6}{\left(a+1\right)\left(a+7\right)}\)
=>x+7=6
=>x=6-7
=>x=-1
vậy x=-1
\(\frac{1}{a+1}-\frac{1}{a+7}=\frac{\left(a+7\right)-\left(a+1\right)}{\left(a+1\right)\left(a+7\right)}=\frac{6}{\left(a+1\right)\left(a+7\right)}\)=> x + 7 = 6 => x = -1
Tính nhanh
A) (1 + 1/4) x (1+ 1/5) x(1+ 1/6) x....x (1+ 1/99)
B) 7/ 1x2 + 7/ 2x3 + 7/ 3x4 + ...... + 7/ 13x14
C) A = 1+ 1/3 +1/9 +1/27 + 1/81 +1/243
a, A x 6/7 + 1/7 x 2/7 + 1/7 x 5/7
b, 4/9 x 13/3 + 4/3 x 40/9
c
A = 290 - 18 X 1 + 567 : 17
B = 1/7 x 3 va 1/11 - 1/7 x 9/11 -1/7
tim a va b
\(A=290-18\times1+567:17\)
\(A=290-18+\frac{567}{17}\)
\(A=272+\frac{567}{17}\)
\(A=\frac{4624}{17}+\frac{567}{17}\)
\(A=\frac{5191}{17}\).
\(B=\frac{1}{7}\times3\frac{1}{11}-\frac{1}{7}\times\frac{9}{11}-\frac{1}{7}\)
\(B=\frac{1}{7}\times\frac{34}{11}-\frac{1}{7}\times\frac{9}{11}-\frac{1}{7}\)
\(B=\left(\frac{34}{11}-\frac{9}{11}-1\right)\times\frac{1}{7}\)
\(B=\left(\frac{25}{11}-1\right)\times\frac{1}{7}\)
\(B=\frac{14}{11}\times\frac{1}{7}\)
\(B=\frac{87}{77}\)
Chúc bạn hok tốt !
cú t ccau oiii ét ô ét giải giúp t bài này zới
4,7 : 0,25 + 5,3 x 4
3x ( a - 2) +150 = 240
1/9 + a + 7/12 = 17/18
( 1/2 x 1/3 + 1/3 x 1/4 + 1/4 x 1/5 + 1/5 x 1/6 + 1/6 x 1/7 + 1/7 x 1/8 ) x a = 9/16
\(4,7\div0,25+5,3\times4\)
\(=18,8+21,2\)
\(=40\)
\(3\times\left(a-2\right)+150=240\)
\(3\times\left(a-2\right)=90\)
\(a-2=30\)
\(a=32\)
\(\dfrac{1}{9}+a+\dfrac{7}{12}=\dfrac{17}{18}\)
\(\dfrac{1}{9}+a=\dfrac{13}{36}\)
\(a=\dfrac{1}{4}\)
\(\left(\dfrac{1}{2}\times\dfrac{1}{3}+\dfrac{1}{3}\times\dfrac{1}{4}+\dfrac{1}{4}\times\dfrac{1}{5}+\dfrac{1}{5}\times\dfrac{1}{6}+\dfrac{1}{6}\times\dfrac{1}{7}+\dfrac{1}{7}\times\dfrac{1}{8}\right)\times a=\dfrac{9}{16}\)
\(\left(\dfrac{1}{2\times3}+\dfrac{1}{3\times4}+\dfrac{1}{4\times5}+\dfrac{1}{5\times6}+\dfrac{1}{6\times7}+\dfrac{1}{7\times8}\right)\times a=\dfrac{9}{16}\)
\(\left(\dfrac{1}{2}-\dfrac{1}{8}\right)\times a=\dfrac{9}{16}\)
\(\dfrac{3}{8}\times a=\dfrac{9}{16}\)
\(a=\dfrac{3}{2}\)