x:8=3721 24 860 : x=5
Tìm x:
a, x : 8 = 3721
b, 24860 : x = 5
c, 49623 + x = 78578
d, 78026 – x = 69375
x:8=3721 24860:x=5 49623+x=78578 78026-x=69637
x:8=3721 24860:x=5 49623+x=78578 78026-x=69637
x=3721x8 x=24860:5 x=78578-49623 x=78026-69637
x=29768 x=4972 x=28955 x=8389
x=3721*8
x=29768
x =24860:5
x =4972
x =78578-49623
x =28955
x =78026-69637
x = 8389
Tìm x
a, 580 :( x -24 ) =329 -150 : 2
b, 7 (x-1 ) +35= 25 + 279 :9
c,4 ( 2x+ 7 ) -3 (3x -2 ) =24
d,( x-1 ) (x-2) =3(x-1)
e,( x+ 3 ) + ( x+7 ) + ( x + 11 ) + ........+ ( x+ 79 ) =860
a, ĐK: \(x\ne24\)
580 :( x -24 ) =329 -150 : 2
<=> 580 :( x -24 ) = 329 - 75
<=> 580 :( x -24 ) = 254
<=> x - 24 = \(\frac{290}{127}\)
<=> x = \(\frac{3338}{127}\left(TM\right)\)
Vậy \(x=\frac{3338}{127}\)
b, 7 (x-1 ) +35= 25 + 279 :9
<=> 7x - 7 + 35 = 25 + 31
<=> 7x +28 = 56
<=> 7x = 28
<=> x = 4
Vậy x =4
c,4 ( 2x+ 7 ) -3 (3x -2 ) =24
<=> 8x + 28 - 9x + 6 = 24
<=> 34 - x = 24
<=> x = 10
Vậy x = 10
d,( x-1 ) (x-2) =3(x-1)
<=> ( x-1 ) (x-2) - 3(x-1) = 0
<=> (x- 1)(x - 2 - 3) = 0
<=> (x -1)(x - 5) = 0
<=> \(\left[{}\begin{matrix}x-1=0\\x-5=0\end{matrix}\right.\) <=> \(\left[{}\begin{matrix}x=1\\x=5\end{matrix}\right.\)
Vậy x ={1; 5}
e, (x + 3) + (x + 7) + (x + 11) + ... + (x + 79) = 860
x + 3 + x + 7 + x + 11 + ... + x + 79 = 860
Có tất cả: (79 - 3) : 4 + 1 = 20 số hạng \(\Rightarrow\) có 20x
hay x + 3 + x + 7 + x + 11 + ... + x + 79 = 860
\(\Rightarrow\) 20x + (3 + 7 + ... + 79) = 860
3 + 7 + ... + 79 = (79 + 3) x 20 : 2 = 820
\(\Rightarrow\) 20x + (3 + 7 + ... + 79) = 860
\(\Rightarrow\) 20x + 820 = 860
\(\Rightarrow\) 20x = 40
\(\Rightarrow\) x = 2
Vậy x = 2
Chúc bn học tốt!
Tính nhẩm:
8 x 5 =
8 x 4 =
8 x 6 =
8 x 3 =
40 : 8 =
32 : 8 =
48 : 8 =
24 : 8 =
40 : 5 =
32 : 4 =
48 : 6 =
24 : 3 =
Học sinh nhẩm và ghi:
8 x 5 = 40
8 x 4 = 32
8 x 6 = 48
8 x 3 = 24
40 : 8 = 5
32 : 8 = 4
48 : 8 = 6
24 : 8 = 3
40 : 5 = 8
32 : 4 = 8
48 : 6 = 8
24 : 3 = 8
(chú ý: mối quan hệ giữa nhân và chia)
Tính nhẩm:
8 x 5 = 40
8 x 4 = 32
8 x 6 = 48
8 x 3 = 24
40 : 8 = 5
32 : 8 = 4
48 : 8 = 6
24 : 8 = 3
40 : 5 = 8
32 : 4 = 8
48 : 6 = 8
24 : 3 = 8
Bài 2: Tìm x
a) x - 2/11 = -5/11
b) x - 1/24 = -1/8 + 5/6
c) 5/8 - x = 1/9 - (-5/4)
d) 8/23 . 46/24 - x = 1/3
e) 1/5 : x = 1/5 + 1/7
a: x=-5/11+2/11=-3/11
b: =>x=-3/24+20/24+1/24=18/24=3/4
c: =>5/8-x=1/9+5/4=4/36+45/36=49/36
=>x=5/8-49/36=-53/72
d: =>2/3-x=1/3
=>x=1/3
e: =>1/5:x=12/35
=>x=7/12
a.x/60=-3/4
b. 2/5=12/x
c. x-5/7 =6/21
dx+7/8 =63/24
e x/6=24/x
f .x+5= 4/x+5
g. x+12/x+8=4/3
h. x+9/x+7=9/8
a)\(\dfrac{x}{60}=-\dfrac{3}{4}\)
\(\Rightarrow x\cdot4=60\cdot\left(-3\right)\)
\(x\cdot4=-180\)
x=45
b)\(\dfrac{2}{5}=\dfrac{12}{x}\)
\(\Rightarrow2x=5\cdot12\)
\(2x=60\)
x=30
c)\(x-\dfrac{5}{7}=\dfrac{6}{21}\)
\(x=\dfrac{2}{7}+\dfrac{5}{7}\)
x=1
d)\(x+\dfrac{7}{8}=\dfrac{63}{24}\)
\(x=\dfrac{21}{8}-\dfrac{7}{8}\)
\(\dfrac{14}{8}\)
a)\(\dfrac{x}{60}=\dfrac{-3}{4}\Rightarrow x=\dfrac{-3.60}{4}=-45\)
b)\(\dfrac{2}{5}=\dfrac{12}{x}\Rightarrow x=\dfrac{5.12}{2}=30\)
1. tinh :
a) 15/8 + 3/4 - 5/12
b) 11/24 x 12/33 + 5/6
c) 15/8 + 7/24 : 5/8
2 . tim x, biet :
a) x + 5/8 : 3/4 = 17/9
b) x - 5/9 x 18/15 = 1/3
c) x x7/8 - 5/8 = 13/24
d) X x1/7 + X x 1/4 + X x 1/4 =18
giup mik nhanh nha. mik can gap lam
a)15/8+3/4-5/12
=45+18-10/24
=53/24
b)11/24.12/33+5/6
=11.12/12.2.11.3+5/6
=1/6+5/6
=6/6=1
c)15/8+7/24:5/8
=15/8+7/24.8/5
=15/8+7.8/3.8.5
=15/8+7/15
=đề sai, nếu đúng thì như này
=8/15+7/15
=15/15=1
(x+3)+(x+7)+(x+11)+...+(x+79)=860
(x+3)+(x+7)+(x+11)+...+(x+79)=860
(x+x+x+...+x) + (3+7+11+...+79)=860
Số lượng số hạng x là:
(79 - 3):4 + 1= 20(số hạng) (10 cặp số hạng)
Ta tiếp tục tính:
(x+x+x+...+x) + (3+7+11+...+79)=860
\(20\times X+\left(79+3\right)\times10=860\\ 20\times X+820=860\\ 20\times X=860-820=40\\ X=\dfrac{40}{20}=2\)
Vậy: X=2
7 x 6 + 7 x 5 + 7 x 2 8 x 3 + 8 x 4 + 24 5 x 5 + 10 + 5 x 3
\(7*(6+5+2)=7*13=91\)
\(8*(3+4+3)=8*10=80\)
\(5*(5+2+3)=5*10=50\) nhé
7 x 6 + 7 x 5 + 7 x 2
=7 x (6+5+2)=7 x 13=91
8 x 3 + 8 x 4 + 24
=8 x (3+4) + 24=8 x 7 +24 =56 + 24=80
5 x 5 + 10 + 5 x 3
=5 x (10+3)=5 x 13=65
7∗(6+5+2)=7∗13=917∗(6+5+2)=7∗13=91
8∗(3+4+3)=8∗10=808∗(3+4+3)=8∗10=80
5∗(5+2+3)=5∗10=505∗(5+2+3)=5∗10=50