Tìm X:
X : 1 7 = 14
Tìm x: Cần gấp ạ
1, -15 + x= - 14 - (-57) 2,(-14) + x - 7 = -10 3, -x - 14 + 32 = -26 4, x-(-19) - (-11) = 0
1, -15 + \(x\) = -14 - (-57)
-15 + \(x\) = -14 + 57
\(x\) = -14 + 57 + 15
\(x\) = 43 + 15
\(x\) = 58
2, (-14) + \(x\) - 7 = -10
-14 + \(x\) - 7 = -10
- 21 + \(x\) = - 10
\(x\) = -10 + 21
\(x\) = 11
3, - \(x\) - 14 + 32 = -26
- \(x\) + 18 = - 26
\(x\) = 18 + 26
\(x\) = 44
Tìm x, biết: x + 2/7=1/2
A.x= 3/14 B. x=2/14 C. x=13/3 D. x=1/5.
X+\(\dfrac{2}{7}\)=\(\dfrac{1}{2}\)
X = \(\dfrac{1}{2}\)-\(\dfrac{2}{7}\)
X = \(\dfrac{3}{14}\)
Chọn đáp án A. \(\dfrac{3}{14}\)
Bài 1: Tìm min (max) nếu có:
A= /3x-9/+1,5 C= -/\(\dfrac{1}{2}\).x-4/+13
B= /x-7/-14 D= -/1,5-x/-14
a: \(A=\left|3x-9\right|+1.5\ge1.5\forall x\)
Dấu '=' xảy ra khi x=3
b: \(B=\left|x-7\right|-14\ge-14\forall x\)
Dấu '=' xảy ra khi x=7
a, Ta có \(A=\left|3x-9\right|+1,5\)
Ta thấy: \(\left|3x-9\right|\ge0\Rightarrow\left|3x-9\right|+1,5\ge1,5\Rightarrow A\ge1,5\)
Dấy"=" xảy ra \(\Leftrightarrow3x-9=0\Leftrightarrow3x=9\Leftrightarrow x=3\)
Vậy \(A_{min}=1,5\Leftrightarrow x=0\)
b, Ta có \(B=\left|x-7\right|-14\)
Ta thấy: \(\left|x-7\right|\ge0\Rightarrow\left|x-7\right|-14\ge-14\Rightarrow B\ge-14\)
Dấu "=" xảy ra \(\Leftrightarrow x-7=0\Leftrightarrow x=7\)
Vậy \(B_{min}=-14\Leftrightarrow x=7\)
c, Ta có: \(C=-\left|\dfrac{1}{2}x-4\right|+13\Rightarrow C=13-\left|\dfrac{1}{2}x-4\right|\)
Ta thấy: \(\left|\dfrac{1}{2}x-4\right|\ge0\Rightarrow13-\left|\dfrac{1}{2}x-4\right|\le13\Rightarrow C\le13\)
Dấu "=" xảy ra \(\Leftrightarrow\dfrac{1}{2}x-4=0\Leftrightarrow\dfrac{1}{2}x=4\Leftrightarrow x=8\)
Vậy \(C_{max}=13\Leftrightarrow x=8\)
d, Ta có: \(D=-\left|1,5-x\right|-14\Rightarrow D=-14-\left|1,5-x\right|\)
Ta thấy: \(\left|1,5-x\right|\ge0\Rightarrow-14-\left|1,5-x\right|\le-14\Rightarrow D\le-14\)
Dấu "=" xảy ra\(\Leftrightarrow1,5-x=0\Rightarrow x=1,5\)
Vậy \(D_{max}=-14\Leftrightarrow x=1,5\)
Hoctot
bài 1 : Tìm x
a) 5 + ( x + 27 ) = 64
b) 64 - ( x - 2 ) = 25
c) 7 - ( x + 5 ) + 14 = 343
d) 5 . x - 25 = 10
e) 4 . ( x - 5 ) - 8 = 48
f) 49 - ( 15 + x ) = 12
g) 49 - 7. ( 13 - x ) = 14
h) 155 - 10. ( x + 1 ) = 55
5 + ( x + 27 ) = 64
( x + 27 ) = 64 - 5 ( x + 27 ) = 59 x = 59 - 27 x = 32a) \(\Rightarrow x+27=59\Rightarrow x=32\)
b) \(\Rightarrow x-2=39\Rightarrow x=41\)
c) \(\Rightarrow x+5=-322\Rightarrow x=-327\)
d) \(\Rightarrow5x=35\Rightarrow x=7\)
e) \(\Rightarrow4\left(x-5\right)=56\Rightarrow x-5=14\Rightarrow x=19\)
f) \(\Rightarrow15+x=37\Rightarrow x=22\)
g) \(\Rightarrow7\left(13-x\right)=35\Rightarrow13-x=5\Rightarrow x=8\)
h) \(\Rightarrow10\left(x+1\right)=100\Rightarrow x+1=10\Rightarrow x=9\)
Bài 1 :Tìm x:
|0,75x - 1/5|+4/7=1 và 4/7
Bài 2 : Tính:
1/2+1/14+1/35+...+1/x (x + 3)÷2=9/14
Tìm x:
x : 3/4= 9/14 - 1/7
X x 1/2 - X x 1/4 = 2/3
help mình
\(x:\dfrac{3}{4}\) = \(\dfrac{9}{14}-\dfrac{1}{7}\)
\(x:\dfrac{3}{4}\) = \(\dfrac{1}{2}\)
\(x=\dfrac{1}{2}\) x \(\dfrac{3}{4}\)
\(x=\dfrac{3}{8}\)
\(x\)x \(\dfrac{1}{2}-\dfrac{1}{4}\)=\(\dfrac{2}{3}\)
\(x\) x \(\dfrac{1}{4}\) =\(\dfrac{2}{3}\)
\(x\) = \(\dfrac{2}{3}:\dfrac{1}{4}\)
\(x\) \(\dfrac{8}{3}\)
Tìm X biết : X-3/7=9/14-1/2
Tìm x, biết: a) x-5/8=1/4. b) 4/7:x=-5/14=> dấu âm ở giữ phân số 5/14
a) \(x-\dfrac{5}{8}=\dfrac{1}{4}\)
\(\Rightarrow x=\dfrac{1}{4}+\dfrac{5}{8}\)
\(\Rightarrow x=\dfrac{2}{8}+\dfrac{5}{8}=\dfrac{7}{8}\)
b) \(\dfrac{4}{7}:x=-\dfrac{5}{14}\)
\(\Rightarrow x=\dfrac{4}{7}:-\dfrac{5}{14}\)
\(\Rightarrow x=-\dfrac{8}{5}\)
a) \(x-\dfrac{5}{8}=\dfrac{1}{4}\)
\(x=\dfrac{1}{4}+\dfrac{5}{8}=\dfrac{2}{8}+\dfrac{5}{8}\)
\(x=\dfrac{7}{8}\)
b) \(\dfrac{4}{7}:x=-\dfrac{5}{14}\)
\(x=\dfrac{4}{7}:\left(-\dfrac{5}{14}\right)=\dfrac{4}{7}.\left(-\dfrac{14}{5}\right)\)
\(x=-\dfrac{8}{5}\)
a] x-5/8=1/4
x = 1/4 + 5/8
X = 7/8
B] 4/7:x= -5/14
x= 4/7 : -5/14
x= -8/5
Dạng 2 : Tìm x Bài 1: Tìm x biết :
a) ( x – 16 ) – 74 = 0 b) (3 x – 5) .7 mũ 3 = 7 mũ 4
c) 560 – 13x = 365 d) 275 – 7( x + 1) = 100
e) 3 x 7 14 3.2 mũ 3 f) 7x – 49 = 105
g) 5x – 16 = 14 h) 3x – 138 = 23 . 2 2
1 " Tìm x "
12 x ( 5 -x ) - 7 x ( x - 5 ) = 14
12 x (5-x) -7 x (x-5) =14
12 x (5-x) +7 x (5-x) =14
(5-x ) x (12+7) =14
(5-x) x19 =14
5-x =14 :19=14/19
x =5 - 14/19 =81/19