Tìm x
71,24=71,x4
5x8,72=598,72
x100=0,08
278/10=2x,8
71,24=71,x4.Tìm x
\(71.24=71.x4\)
Nếu \(71.24=71.x4\)
\(\Rightarrow x=2\)
Vậy \(x=2\)
tìm giá trị của chữ x,biết:
a)71,24 =71, x 4 b)5x8,72=598,72
c) x/100=0,08 d)278/100=2x,8
bài này là số thập phân nha.X này là chữ x ko phải là dấu nhân đâu
a) 71,24=71,24
b) 598,72=598,72
c) 8/100=0,08
d) 278/100=27,8
Xong rồi nè bạn. Nhớ k mk nha.
a,71,24=71,24
b,598,72=598,72
c,8/100=0,08
d,278/100=27,8
Tìm số tự nhiên x biết:
a) 25 + 7x = 144
b) 33 - 12x = 9
c) 128 - 3(x + 4) = 23
d) 71 + (726 - 3x).5 = 2246
e) 720 : [41 - (2x + 5)] = 40
f) (10 - 4x) + 120 : 8 = 16 + 1
g) x + 9x + 7x + 5x = 2244
h) (x + 1) + (x + 2) + (x + 3) +...+ (x + 100) = 5750
i) 1 + 2 + 3 +...+ x = 500500
j) 51 + 52 + 53 +...+ x = 18825
a: Ta có: \(7x+25=144\)
\(\Leftrightarrow7x=119\)
hay x=17
b: Ta có: \(33-12x=9\)
\(\Leftrightarrow12x=24\)
hay x=2
c: Ta có: \(128-3\left(x+4\right)=23\)
\(\Leftrightarrow3\left(x+4\right)=105\)
\(\Leftrightarrow x+4=35\)
hay x=31
d: Ta có: \(71+\left(726-3x\right)\cdot5=2246\)
\(\Leftrightarrow5\left(726-3x\right)=2175\)
\(\Leftrightarrow726-3x=435\)
\(\Leftrightarrow3x=291\)
hay x=97
e: Ta có: \(720:\left[41-\left(2x+5\right)\right]=40\)
\(\Leftrightarrow41-\left(2x+5\right)=18\)
\(\Leftrightarrow2x+5=23\)
\(\Leftrightarrow2x=18\)
hay x=9
f: Ta có: \(10-4x+120:8=16+1\)
\(\Leftrightarrow4x=17-25=-8\)
hay x=-2
g: Ta có: \(x+9x+7x+5x=2244\)
\(\Leftrightarrow22x=2244\)
hay x=102
h: Ta có: \(\left(x+1\right)+\left(x+2\right)+\left(x+3\right)+...+\left(x+100\right)=5750\)
\(\Leftrightarrow100x+5050=5750\)
\(\Leftrightarrow100x=700\)
hay x=7
22+4(2x-4)=-26
71-(8-x)=-12+71
\(\left(+\right)22+4\left(2x-4\right)=-26\)
\(\Leftrightarrow22+8x-16=-26\)
\(\Leftrightarrow x=\dfrac{-26-22+16}{8}=-4\)
\(\left(+\right)71-\left(8-x\right)=-12+71\)
\(\Leftrightarrow71-8+x=-12+71\)
\(\Leftrightarrow x=-12+71-71+8=-4\)
22+4.(2x-4)=-26
<=> 4.(2x-4)= -26-22
<=>4.(2x-4)=-48
<=>2x-4=-48:4=-12
<=>2x=-12+4=-8
<=>x=-8:2=-4
Vậy: S={-4}
---
71-(8-x)=-12+71
<=>71-8+x=83
<=>x=83+8-71=20
Vậy S={20}
\(22+4\left(2x-4\right)=-26\)
\(4\left(2x-4\right)=-26-22=-48\)
\(2x-4=-48:4=-12\)
\(2x=-12+4=-8\)
\(x=-8:2=-4\)
tìm x 71 x 2 - 6 (2x + 5) = 100
71 x 2 - 6 (2x + 5) = 100
142-6.(2x+5)=100
6.(2x+5)=142-100
6.(2x+5)=42
2x+5 =42:6
2x+5 =7
2x =7-5
2x =2
x =2:2
x =1
3. Tìm x, biết:
a) 2x + 8 ≤ 0
b) 4x-7 ≥ 2x -5
c) (2x-8)(15-3x)>0
d) (10-2x)(8+2x)≤0
3. Tìm x, biết: a) 2x + 8 ≤ 0 b) 4x-7 ≥ 2x -5 c) (2x-8)(15-3x)>0 d) (10-2x)(8+2x)≤0
a) 2x+8≤ 0
⇔2x≤-8
⇔x≤-4
b) 4x-7 ≥ 2x -5
⇔2x-12 ≥ 0
⇔2x≥12
⇔x≥6
c) (2x-8)(15-3x)>0
TH1: 2x-8>0 ⇒x>4
15-3x>0⇒x<5
TH2: 2x-8<0 ⇒x<4
15-3x<0⇒x>5 (vô lí)
vậy 4<x<5
Câu 1
-2x – 40 = (5 – x) – (-15 + 60)
d) -10 –(5 – x) = -12
Câu 2: Tính tổng các số nguyên x thỏa mãn: .
Câu 3: Tìm n Z, biết : -10 (n – 5)
c) -2x-40=(5-x)-(-15+60)
-2x-40=5-x+15-60
-2x+x=5+15-60+40
-x=-5
x=5
Vậy x=5
d) -10-(5-x)=-12
5-x =-10+12
5-x =2
x =5-2
x =3
Vậy x =3
11. Tìm x
a) (2x-8)(10+2x)≥0
b) (|x|+5)(x-3)<0
a) Ta có: \(\left(2x-8\right)\left(2x+10\right)\ge0\)
\(\Leftrightarrow\left[{}\begin{matrix}2x-8\ge0\\2x+10\le0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x\ge4\\x\le-5\end{matrix}\right.\)
b) Ta có: \(\left(\left|x\right|+5\right)\left(x-3\right)< 0\)
nên x-3<0
hay x<3