Tìm x:
a) 1996 + x = 2002
b) x x 3 = 9861
c) x : 4 = 250
Tìm x:
( x - 5 ) x ( 1995 x 1996 + 1997 x 1996 ) = 1234 x 5678 x ( 630 - 315 x 2 ) : 1996
(x-5) x ( 1995 x 196 + 1997 x 1996) = 0
x-5 = 0 : ( 1995 x 196 + 1997 x 1996)
x-5 = 0
x= 0+5
x= 5
Tìm x:
a, x(2x – 3) – 2(3 – 2x) = 0
b, (x – 3)(x2 + 3x + 9) – x(x + 2)(x – 2) = 1
c, 4x2 + 4x – 6 = 2
d, 2x2 + 7x + 3 = 0
\(a,\Leftrightarrow\left(2x-3\right)\left(x+2\right)=0\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{3}{2}\\x=-2\end{matrix}\right.\\ b,\Leftrightarrow x^3-27-x^3+4x=1\\ \Leftrightarrow4x=28\Leftrightarrow x=7\\ c,\Leftrightarrow4x^2-4x-8=0\\ \Leftrightarrow x^2-x-2=0\\ \Leftrightarrow\left(x-2\right)\left(x+1\right)=0\Leftrightarrow\left[{}\begin{matrix}x=2\\x=-1\end{matrix}\right.\\ d,\Leftrightarrow2x^2+6x+x+3=0\\ \Leftrightarrow\left(x+3\right)\left(2x+1\right)=0\Leftrightarrow\left[{}\begin{matrix}x=-3\\x=-\dfrac{1}{2}\end{matrix}\right.\)
k) 4 x 113 x 25 - 5 x 112 x 20
p) 1235 x 6789 x ( 630 - 315 x 2 ) :1996
l) 54 x 113 + 45 x 113 + 113
u) ( 500 x 9 - 250 x 18 ) x ( 1 +2 +3 +.......+ 9 )
k) 4 x 113 x 25 - 5 x 112 x 20
= (4 x 25) x 113 - (5 x 20) x 112
= 100 x 113 - 100 x 112
= 100 x (113 - 112)
= 100
p) 1235 x 6789 x (630 - 315 x 2) : 1996
= 1235 x 6789 x (630 - 630) : 1996
= 1235 x 6789 x 0 : 1996
= 0
l) 54 x 113 + 45 x 113 + 113
= 113 (54 + 45 + 1)
= 113 x 100
= 11300
u) (500 x 9 - 250 x 18) x (1 + 2 + 3 + ... + 9)
= (2 x 250 x 9 - 250 x 2 x 9) x (1 +2 + 3 + ... + 9)
= 0 x (1 + 2 + 3 + ... + 9)
= 0
(1995 : 0,25 + 1996 :4) x 101 x 102 x (3 : 4 - 0,75)
1996 x 1997 x (12 - 3 : 0,25) + 1996 : 0,25 + 1995 x 4
Tính nhanh phép tính trên
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Mình xin lỗi câu này mình ko biết
tìm số tự nhiên x biết:
a. 326 - 2x = 78
b. 42 . 5 - (3x + 6) = 34
c. 4x : 64 = 4250
d. (x + 1) + (x + 2) + (x + 3) +...+ (x + 29) + (x + 30) = 495
a) \(326-2x=78\Rightarrow2x=326-78=248\)
\(\Rightarrow x=248:2=124\)
b) \(42.5-\left(3x+6\right)=3^4\Rightarrow210-\left(3x+6\right)=81\)
\(\Rightarrow3x+6=210-81=129\Rightarrow3x=129-6=123\)
\(\Rightarrow x=123:3=41\)
a, 326 -2x =78
\(\Rightarrow\)2x=326-78=248
\(\Rightarrow\)x=248/2=124
b,\(42.5-\left(3x+6\right)=3^4\)
\(\Rightarrow\)\(210-3x-6=81\)
\(\Rightarrow\)3x=123
\(\Rightarrow\)x=123/3=41
c, \(4^x:64=4^{250}\)
\(\Rightarrow\)\(4^x:4^3=4^{250}\)
\(\Rightarrow\)x=253
d, \(30x+1+2+3+...+30=495\)
\(\Rightarrow\)\(30x+465=495\)
\(\Rightarrow\)\(x=1\)
Tìm x:
a) X x 3 x 5 = 2,7 b) 1,2 : X x 4 = 20
a: \(x\cdot3\cdot5=2,7\)
=>\(x\cdot15=2,7\)
=>\(x=\dfrac{2,7}{15}=0,18\)
b: \(1,2:x\cdot4=20\)
=>\(1,2:x=20:4=5\)
=>\(x=1,2:5=0,24\)
Tìm x:
a)x.(x+7)-(x-2).(x+3)=0
b)(x+2)2-(x2-4)=0
a: \(x\left(x+7\right)-\left(x-2\right)\left(x+3\right)=0\)
\(\Leftrightarrow x^2+7x-x^2-x+6=0\)
hay x=-1
b: Ta có: \(\left(x+2\right)^2-\left(x^2-4\right)=0\)
\(\Leftrightarrow x+2=0\)
hay x=-2
b. (x + 2)2 - x2 + 4 = 0
<=> (x + 2 - x)(x + 2 + x) + 4 = 0
<=> 2(2 + 2x) + 4 = 0
<=> 4(1 + x) + 4 = 0
<=> 4(1 + x) = -4
<=> 1 + x = -1
<=> x = -1 - 1
<=> x = -2
\(a,\) \(x\left(x+7\right)-\left(x-2\right)\left(x+3\right)\)
\(\Leftrightarrow x^2+7x-x^2-3x+2x+6\\ \Leftrightarrow6x=0\\ \Leftrightarrow x=0\)
\(Vậy...\)
\(b,\) \(\left(x+2\right)^2-\left(x^2-4\right)=0\)
\(\Leftrightarrow x^2+4x+4-x^2+4=0\\ \Leftrightarrow4x+8=0\\ \Leftrightarrow x=-2\)
Câu 3: (1 diểm) Tìm x:
a) (x + 3)^2 - x(x - 4) = 39
b) x(x - 9) + 2x -18 = 0
a)=> x2 + 6x + 9 - x2 + 4x = 39 => 10x = 30 => x = 3
b) => x(x - 9) + 2(x -9) = 0 => (x+2)(x-9) = 0
+)th1: x + 2 = 0 => x = -2
+)th2: x - 9 =0 => x = 9
Tìm x:
a)x(x+4)+(5+x)(5-x)=3
b)(2x-3)^2=(4x+3)^2
mình cảm ơn
\(a,\Rightarrow x^2+4x+25-x^2=3\\ \Rightarrow4x=-22\Rightarrow x=-\dfrac{11}{2}\\ b,\Rightarrow\left(2x-3-4x-3\right)\left(2x-3+4x+3\right)=0\\ \Rightarrow6x\left(-2x-6\right)=0\Rightarrow\left[{}\begin{matrix}x=-3\\x=0\end{matrix}\right.\)