tìm xϵz , biết :
a) 2x2 - 3 = 29
b) -6x - (-7) = 25
c) 46 - (x - 11 ) = -48
tìm xϵz , biết :
a) 2x^2 - 3 = 29
b) -6x - (-7) = 25
c) 46 - (x - 11 ) = -48
a/\(2\cdot x^2-3=29\)
\(2\cdot x^2=29+3=32\)
\(x^2=\frac{32}{2}=16\)
=> \(x=\sqrt{16}=4\)
b/\(\left(-6\right)x-\left(-7\right)=25\)
\(\left(-6\right)x+7=25\)
\(\left(-6\right)x=25-7=18\)
\(x=\frac{18}{-6}=-3\)
c/ \(46-\left(x-11\right)=-48\)
\(46-x+11=-48\)
\(x=46-\left[\left(-48\right)-11\right]=105\)
a) 2x^2 -3= 29
2x^2 = 32
x^2 = 16
x = +4 ; -4
b) -6x - (-7) =25
-6x +7 =25
-6x = 18
x = -3
c) 46 - (x-11) = -48
46 -x +11 = -48
46 -x = -59
x = 105
a/\(2x^2-3=29\)
\(2x^2=29+3=32\)
\(x^2=\frac{32}{2}=16\)
\(x=\sqrt{16}=4\)
b/\(\left(-6\right)x-\left(-7\right)=25\)
\(\left(-6\right)x+7=25\)
\(\left(-6\right)x=25-7=18\)
\(x=\frac{18}{-6}=-3\)
c/\(46-\left(x-11\right)=-48\)
\(46-x+11=-48\)
\(x=46-\left[\left(-48\right)-11\right]=105\)
1) (x-2).(x+4)=0
2) (x-2).(x+15)=0
3) (7-x).(x+19)=0
4) -5<x<1
5) (x-3)(x-5)<0
6) 2x2-3=29
7) -6x-(-7)=25
8) 46-(x-11) = -48
1) \(\left(x-2\right)\left(x+4\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}x-2=0\\x+4=0\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}x=2\\x=-4\end{matrix}\right.\)
2) \(\left(x-2\right)\left(x+15\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}x-2=0\\x+15=0\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}x=2\\x=-15\end{matrix}\right.\)
3) \(\left(7-x\right)\left(x+19\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}7-x=0\\x+19=0\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}x=7\\x=-19\end{matrix}\right.\)
4) \(-5< x< 1\)
\(\Rightarrow x\in\left\{-1;-3;-2;-1;0\right\}\)
5) \(\left(x-3\right)\left(x-5\right)< 0\)
\(\Rightarrow\left[{}\begin{matrix}x-3>0\\x-5< 0\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}x>3\\x< 5\end{matrix}\right.\)
\(\Rightarrow3< x< 5\)
6) \(2x^2-3=29\)
\(\Rightarrow2x^2=29+3\)
\(\Rightarrow2x^2=32\)
\(\Rightarrow x^2=\dfrac{32}{2}\)
\(\Rightarrow x^2=16\)
\(\Rightarrow x^2=4^2\)
\(\Rightarrow\left[{}\begin{matrix}x=4\\x=-4\end{matrix}\right.\)
7) \(-6x-\left(-7\right)=25\)
\(\Rightarrow-6x+7=25\)
\(\Rightarrow-6x=25-7\)
\(\Rightarrow-6x=18\)
\(\Rightarrow x=\dfrac{18}{-6}\)
\(\Rightarrow x=-3\)
8) \(46-\left(x-11\right)=-48\)
\(\Rightarrow x-11=48+46\)
\(\Rightarrow x-11=94\)
\(\Rightarrow x=94+11\)
\(\Rightarrow x=105\)
1: (x-2)(x+4)=0
=>x-2=0 hoặc x+4=0
=>x=2 hoặc x=-4
2: (x-2)(x+15)=0
=>x-2=0 hoặc x+15=0
=>x=2 hoặc x=-15
3: (7-x)(x+19)=0
=>7-x=0 hoặc x+19=0
=>x=7 hoặc x=-19
4: -5<x<1
=>\(x\in\left\{-4;-3;-2;-1;0\right\}\)
5: (x-3)(x-5)<0
=>x-3>0 và x-5<0
=>3<x<5
6: 2x^2-3=29
=>2x^2=32
=>x^2=16
=>x=4 hoặc x=-4
7: -6x-(-7)=25
=>-6x=25-7=18
=>x=-3
8: 46-(x-11)=-48
=>x-11=46+48=94
=>x=94+11=105
1 tìm x
a, 2x2 -3=29
b, -6x -(-7) =25
c, 46 - (x-11)=-48
2 cho biểu thức: A= (-a+b-c) - (-a -b-c)
a) rút gọn A b) tính giá trị của A khi a= 1;b=-1;c=-2
1.a X= \(\sqrt{\frac{32}{2}}\)
\(\Leftrightarrow x=4\)
b.x= \(\frac{-7+25}{-6}\)
x= -3
c. x=\(\frac{-11-46-48}{-1}\)
x=105
2. aA= -a+b-c+a+b+c
A= 2b
b. A= 2.-1= -2
tìm x:
a, -12 ( x- 5) + 7 ( 3 - x)= 5
b,-5 < x < 1
c,|x| < 3
d,(x - 3)(x - 5) < 0
e, 2x^2 - 3 = 29
g, -6x - (-7) = 25
h, 46 - ( x - 11) = -48
GIÚP VS, CHIỀU NAY MIK PHẢI NỘP RỒI
-12 .( x - 5 ) + 7 .( 3 - x ) = 5
-12x - ( -60 ) + 21 - 7x = 5
-12x + 60 + 21 - 7x = 5
( -12x - 7x ) + ( 60 + 21 ) = 5
-19x + 81 = 5
-19x = 5 - 81
-19x = -76
x = ( -76 ) : ( -19 )
x = 4
\(-5< x< 1\)
\(\Rightarrow\left\{-4;-3;-2;-1;0\right\}\)
Hok tốt
\(-5< x< 1\)
\(\Rightarrow x\in\left\{-4;-3;-2;-1;0\right\}\)
Hok tốt
13) –12(x -5) + 7(3 -x) = 5
14) (x –2).(x + 4) = 0
15) (x –2).( x + 15) = 0
16) (7–x).( x + 19) = 0
17) -5<x<1
18) /x/<3
19) (x –3)(x –5) < 0
20) 2x2–3 = 29
21) –6x –(–7) = 25
22) 46 –( x –11 ) = –48
13) –12(x -5) + 7(3 -x) = 5
→ -12x + 60 + 21 - 7x = 5
→ -12x - 7x = 5 - 60 - 21
→ -19x = -76
→ x = -76 : ( - 19 )
→ x = 4
14) (x –2).(x + 4) = 0
→ ( x - 2 ) . ( x + 4 ) = 0 ↔ x - 2 = 0 hoặc x + 4 = 0 ( chọn 1 cách thôi nhé )
→ x = 0 + 2 = 2 hoặc x = 0 - 4 = -4
15) (x –2).( x + 15) = 0 ( làm giống câu trên )
16) (7–x).( x + 19) = 0 ( làm giống câu trên )
17) -5<x<1
→ x ϵ -4 ; -3 ; -2 ; -1 ; 0
18) /x/<3
→ x ϵ -2 ; -1 ; 0 ; 1 ; 2
19) (x –3)(x –5) < 0
→ x - 3 . x - 5 < 0
→ 2x - 15 < 0
→ 2x < 0 + 15 = 15
→ x < 15 : 2 = 7,5
→ x ϵ ....... ( bạn tự ghi nhé )
20) 2x2–3 = 29( đề bài sai )
21) –6x –(–7) = 25
→ -6x + 7 = 25
→ -6x = 25 - 7 = 18
→ x = 18 : ( - 6 ) = -3
22) 46 –( x –11 ) = –48
→ 46 - x + 11 = -48
→ -x = -48 - 11 - 46 = -105
→ x = 105
Tìm số nguyên x, biết :
a, 3x - 75 = 45 + 3 . ( -25 )
b, 2 . ( -7 ) -11 = 6x + 17
c, 37 . ( 29 - 23 ) - 29 . ( 37 - 23 )
d, -4 . /x-3/=-48
\(a,3x-75=45+3.\left(-25\right)\)
\(3x-75=-30\)
\(3x=45\)
\(x=15\)
\(b,2.\left(-7\right)-11=6x+17\)
\(-14-11-17=6x\)
\(-42=6x\)
\(-7=x\Leftrightarrow x=-7\)
\(d,-4.|x-3|=-48\)
\(|x-3|=12\)
\(\Rightarrow\orbr{\begin{cases}x-3=12\\x-3=-12\end{cases}\Rightarrow\orbr{\begin{cases}x=15\\x=-9\end{cases}}}\)
1: thực hiện phép tính
a)53-76-[-76-(-53)]
b)-87-12-(-48)+(-512)0
c)2+22+23+.....+2100
2 tìm xϵz,biết
a) (x-1)2=1
b)(x+1)3=-1
c)105-(135-7x):9=97
d)(x+7).(3-x)>0
e)3x-3-32=2.32
g)(2x2+1).(4-2x)=0
giúp nhoa
Bài 2:
a: =>x-1=1 hoặc x-1=-1
=>x=2 hoặc x=0
b: =>x+1=-1
hay x=-2
c: =>(135-7x):9=8
=>135-7x=72
=>7x=63
hay x=9
d: =>(x+7)(x-3)<0
=>-7<x<3
e: \(\Leftrightarrow3^{x-3}=18+9=27\)
=>x-3=3
hay x=6
f: =>4-2x=0
hay x=2
a ) | x - 2| = 3
b) -3 | x + 1 | = 9
c) 3 | x - 1 | -5 = 7
d) -12 ( x - 5 ) + 7 ( 3 - x ) = 5
e) ( x - 2 ) . ( x + 15 ) = 0
f) (7 - x ) . ( x + 19 ) = 0
g) ( x - 3 ) (x - 5 ) < 0
h) -6x - (- 7 ) = 25
i) 46 - ( x - 11 ) = -48
i) 46 - ( x - 11 ) = -48
=>x-11=94
=>x=105
Vậy x=105
a ) | x - 2| = 3
=>x-2=3 hoặc x-2=-3
+)x-2=3
=>x=5
+)x-2=-3
=>x=-1
Vậy x=5 hoặc x=-1
(x-2).(x+14)=0
(x-2).(x+4)=0
(7-x).(x+19)=0
(x-3)(x-5)<0
2x^2-3=29
-6x-(-7)=25
46-(x-11)=-48
\(1.\left(x-2\right).\left(x+14\right)=0\)
<=>\(\orbr{\begin{cases}x-2=0\\x+14=0\end{cases}}\)
<=>\(\orbr{\begin{cases}x=2\\x=-14\end{cases}}\)
\(2.\left(x-2\right).\left(x+4\right)=0\)
<=>\(\orbr{\begin{cases}x-2=0\\x+4=0\end{cases}}\)
<=>\(\orbr{\begin{cases}x=2\\x=-4\end{cases}}\)
\(\left(x-2\right)\left(x+14\right)=0\)
\(\Leftrightarrow\orbr{\begin{cases}x-2=0\\x+14=0\end{cases}\Leftrightarrow\orbr{\begin{cases}x=2\\x=-14\end{cases}}}\)
vậy x= 2 hoặc x=-14
\(\left(x-2\right)\left(x+4\right)=0\)
\(\Leftrightarrow\orbr{\begin{cases}x-2=0\\x+4=0\end{cases}\Leftrightarrow\orbr{\begin{cases}x=2\\x=-4\end{cases}}}\)
vậy x=2 hoặc x=-4
\(\left(x-3\right)\left(x-5\right)< 0\)
nên x-3 và x-5 khác dấu
\(th1\Leftrightarrow\orbr{\begin{cases}x-3< 0\\x-5>0\end{cases}\Leftrightarrow\orbr{\begin{cases}x< 3\\x>5\end{cases}}\Leftrightarrow5< x< 3}\left(vl\right)\)
\(th2\Leftrightarrow\orbr{\begin{cases}x-3>0\\x-5< 0\end{cases}\Leftrightarrow\orbr{\begin{cases}x>3\\x< 5\end{cases}}\Leftrightarrow3< x< 5}\left(tm\right)\)
vậy với 3<x<5
thì x=4