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a, 3/4 ÷ x/6 = 0,75
x/6 = 0,75 ÷ 0,75
x/6 = 1
=> x = 6
Vậy x = 6
b, 2,5 . 45/ x = 5/6
45/x = 5/6 ÷ 2,5
45/x = 1/3
=> x = 45 × 3
=> x = 135
Vậy x = 135
c, x/12 + 121,5 = 121,5
x/12 = 121,5 - 121,5
x/12 = 0
=> x = 0
Vậy x = 0
e, 6/8 = 15/x
3/4 = 15/x
=> x = 20
Vậy x = 20
\(F=1\dfrac{1}{5}\times1\dfrac{1}{6}\times1\dfrac{1}{7}\times\cdot\cdot\cdot\times1\dfrac{1}{2019}\times1\dfrac{1}{2020}\)
\(F=\dfrac{6}{5}\times\dfrac{7}{6}\times\dfrac{8}{7}\times\cdot\cdot\cdot\times\dfrac{2020}{2019}\times\dfrac{2021}{2020}\)
\(F=\dfrac{6\times7\times8\times\cdot\cdot\cdot\times2020\times2021}{5\times6\times7\times\cdot\cdot\cdot\times2019\times2020}\)
\(F=\dfrac{2021}{5}\)
\(Huyền\) |
\(f=1^1_5\times1^1_6\times1^1_7\times......\times1^1_{2019}\times1^1_{2022}\)
\(f=\dfrac{6}{5}\times\dfrac{7}{6}\times\dfrac{8}{7}\times....\times\dfrac{2020}{2019}\times\dfrac{2021}{2020}\)
\(f=\dfrac{6\times7\times8\times....\times2020\times2021}{5\times6\times7\times.....\times2019\times2020}\)
\(f=\dfrac{2021}{5}\)
\(#Tarus\)
phải là
X x 3 + X = 12
X x 3 + X x 1 =12
X x (3+1) = 12
X x 4 = 12
X = 12 : 4
X = 3
\(205+\left(45-x\right)=176\)
\(205+45-x=176\)
\(250-x=176\)
\(x=250-176\)
\(x=74\)
- Tính giá trị biểu thức:
a) (2/5 x 25/29) + (3/5 x 25/29)
= (50/145) + (75/145)
= 125/145
b) (5/2 x 3/7) - (3/14 : 6/7)
= 15/14 - (3/14 x 7/6)
= 15/14 - 1/2
= (30/28) - (14/28)
= 16/28
= 4/7
c) (15/4 : 5/12) - (6/5 : 11/15)
= (15/4 x 12/5) - (6/5 x 15/11)
= 180/20 - 90/55
= 9 - 18/11
= (99/11) - (18/11)
= 81/11
= 7 4/11
- Tính giá trị biểu thức:
a) (2/3) + (20/21 x 3/2 x 7/5)
= 2/3 + (60/210)
= 2/3 + 2/7
= (14/21) + (6/21)
= 20/21
b) (5/17 x 21/32 x 47/24 x 0)
= 0
c) (11/3 x 26/7) - (26/7 x 8/3)
= (286/21) - (208/21)
= 78/21
= 3 9/21
= 3 3/7
- Tìm x:
a) (25/8) : x = 5/16
=> (25/8) x (16/5) = x
=> 4 = x
b) x + (7/15) = 6/15
=> x = (6/15) - (7/15)
=> x = -1/15
c) x : (28/49) = 7/12
=> x x (49/28) = 7/12
=> x = (7/12) x (28/49)
=> x = 1/2
- Tìm x:
a) 6 x x = (5/8) : (3/4)
=> 6x = (5/8) x (4/3)
=> 6x = 20/24
=> 6x = 5/6
=> x = (5/6) / 6
=> x = 5/36
câu,b,không,đủ,thông,tin,nhan,bạn.
71 + 65 \(\times\) 4 = ( \(x\) + 10) : \(x\) + 260
(\(x\) + 10) : \(x\) + 260 = 71 + 260
\(\left(x+10\right)\): \(x\) = 71 + 260 - 260
(\(x+10\)): \(x\) = 71
\(x\) + 10 = 71 \(\times\) \(x\)
\(x\times\) 1 + 10 = 71 \(\times\) \(x\)
71 \(\times\) \(x\) - \(x\) \(\times\) 1 = 10
\(x\) \(\times\)( 71 - 1) = 10
\(x\) \(\times\) 70 = 10
\(x\) = 10 : 70
\(x\) = \(\dfrac{1}{7}\)
\(71+65\times4=\left(x+10\right):x+260\)
\(\Leftrightarrow\left(x+10\right):x+260=71+65\times4\)
\(\Leftrightarrow\left(x+10\right):x+260=71+260\)
\(\Leftrightarrow\left(x+10\right):x=71\)
\(\Leftrightarrow\left(\dfrac{x}{x}+10\right):x=71\)
\(\Leftrightarrow\left(1+10\right):x=71\)
\(\Leftrightarrow10:x=71-1\)
\(\Leftrightarrow10:x=70\)
\(\Leftrightarrow x=10:70\)
\(\Leftrightarrow x=\dfrac{10}{70}\)
\(\Rightarrow x=\dfrac{1}{7}\)
Chúc bạn học tốt
3265859:9856=331,36
còn nhiều số phía sau nhưng mik ghi đến đây cx đúng r nên thôi nhé!!!
k cho mik nha
#Họctốt
S=1/(1+2)+1/(1+2+3)+1/(1+2+3+4)+...+1/(1+2+3+4+...+10)
S=1/(2*3/2)+1/(3*4/2)+1/(4*5/2)+...+1/(10*11/2)
S=2(1/(2*3)+1/(3*4)+1/(4*5)+1/(5*6)+...+1/(10*11)
S=2(1/2-1/3+1/3-1/4+1/4-1/5+...+1/10-1/11)
S=2(1/2-1/11)
S=2*9/22
S=9/11
nho k cho minh voi nha
(x+5)(x-4)=0
x+5=0
x-4=0
x=-5
x=4
x=4 hoac -5
k mk nha