tìm x biết
a) / x-6 /+ /x-2/ = 10
b) /x-4/ + /x+5/= 9
giúp mk nha
Tìm x biết
a) -2x(x+3)+x(2x-1)=10
b) (2/3x)(9x/2+1/4)-(3x2x+2)=3
a: -2x(x+3)+x(2x-1)=10
=>-2x^2-6x+2x^2-x=10
=>-7x=10
=>x=-10/7
b: Sửa đề: 2/3x(9/2x+1/4)-(3x^2+2)=3
=>3x^2+1/6x-3x^2-2=3
=>1/6x-2=3
=>x=30
Tìm số nguyên x,y,z biết:
-2/3 = x/-6 = 10/-y =z/9
Giúp mk vs nha! Tks 🤗🤗
\(-\dfrac{2}{3}=\dfrac{x}{-6}\Rightarrow x=\left(-\dfrac{2}{3}\right)\left(-6\right)=4\)
\(-\dfrac{2}{3}=\dfrac{10}{-y}\Rightarrow y=\left(-10\right):\left(-\dfrac{2}{3}\right)=15\)
\(-\dfrac{2}{3}=\dfrac{z}{9}\Rightarrow z=\left(-\dfrac{2}{3}\right).9=-6\)
\(\dfrac{-2}{3}=\dfrac{x}{-6}=\dfrac{10}{-y}=\dfrac{z}{9}\)
\(x=\left(-6.-2\right):3=4;y=\left(-6.10\right):-4=15;z=\left(10.9\right):-15=-6\)
tìm x biết
a) (x-2)3-x(x+1)(x-1)+6x(x-3)=10
b) (x+1)3-(x-1)3-6(x-1)2= -10
c) x3+3x2+3x+28=0
d) x3-6x2+12x-7=0
\(a,PT\Leftrightarrow x^3-6x^2+12x-8-x^3+x+6x^2-18x-10=0\)
\(\Leftrightarrow-5x-18=0\)
\(\Leftrightarrow x=-\dfrac{18}{5}\)
Vậy ...
\(b,PT\Leftrightarrow x^3+3x^2+3x+1-x^3+3x^2-3x+1-6x^2+12x-6+10=0\)
\(\Leftrightarrow12x+6=0\)
\(\Leftrightarrow x=-\dfrac{1}{2}\)
Vậy ...
\(c,PT\Leftrightarrow\left(x+1\right)^3+3^3=0\)
\(\Leftrightarrow\left(x+1+3\right)\left(x^2+2x+1-3x-3+9\right)=0\)
\(\Leftrightarrow\left(x+4\right)\left(x^2-x+7\right)=0\)
Thấy : \(x^2-\dfrac{2.x.1}{2}+\dfrac{1}{4}+\dfrac{27}{4}=\left(x-\dfrac{1}{2}\right)^2+\dfrac{27}{4}\ge\dfrac{27}{4}>0\)
\(\Rightarrow x+4=0\)
\(\Leftrightarrow x=-4\)
Vậy ...
\(d,PT\Leftrightarrow\left(x-2\right)^3+1^3=0\)
\(\Leftrightarrow\left(x-2+1\right)\left(x^2-4x+4-x+2+1\right)=0\)
\(\Leftrightarrow\left(x-1\right)\left(x^2-5x+7\right)=0\)
Thấy : \(x^2-5x+7=x^2-\dfrac{5.x.2}{2}+\dfrac{25}{4}+\dfrac{3}{4}=\left(x-\dfrac{5}{2}\right)^2+\dfrac{3}{4}\ge\dfrac{3}{4}>0\)
\(\Rightarrow x-1=0\)
\(\Leftrightarrow x=1\)
Vậy ...
tìm x e Z biết
a, ( - 3 ) .8 + ( - 4 ). ( - 5 ) + x = - 12
b, x - 6 . ( - 5 ) + 4 . ( - 3 ) = - 18
c, ( - 2 ) . ( - 4 ) . ( - 5 ) - x = 40
giúp mình với nha !
Thanks !
A,-8
B,-36
C,-80
{Mình tính bằng máy tính }
Bài 1: Tìm các số tự nhiên x biết
a) 76 - 6(x-1) = 10
b) 3.4^3 - 7 - 185
c) 5x + 15 chia hết cho x + 2.
Bài 3: Cho D = 6 + 6^2 + 6^3 + 6^4 +...+ 6^120 . Chứng minh D chia hết cho 7. Chia hết cho 43
Bài 1:
a: 76-6(x-1)=10
\(\Leftrightarrow x-1=11\)
hay x=12
c: \(5x+15⋮x+2\)
\(\Leftrightarrow x+2=5\)
hay x=3
Bài 1:
a) 76 - 6 (x - 1) = 10
6 (x - 1) = 76 - 10
6 (x - 1) = 66
x - 1 = 66 : 6
x - 1 = 11
x = 11 + 1
x = 12
b) 3 . 43 - 7 - 185
= 3 . 64 - 7 - 185
= 192 - 7 - 185
= 185 - 185
= 0
tìm x , biết
a) 17/6- x( x-7/6)= 7/4
b) 3/35 - ( 3/5-x)= 2/7
tìm x thuộc Z , biết
3/4-5/6 < x/12 < 1 -( 2/3-1/4)
tìm x biết
a ) 2x-3=x + 1/2
b) 4x- ( x+ 1/2) = 2x - ( 1/2 - 5 )
Bài 1:
a) Ta có: \(\dfrac{17}{6}-x\left(x-\dfrac{7}{6}\right)=\dfrac{7}{4}\)
\(\Leftrightarrow\dfrac{17}{6}-x^2+\dfrac{7}{6}x-\dfrac{7}{4}=0\)
\(\Leftrightarrow-x^2+\dfrac{7}{6}x+\dfrac{13}{12}=0\)
\(\Leftrightarrow-12x^2+14x+13=0\)
\(\Delta=14^2-4\cdot\left(-12\right)\cdot13=196+624=820\)
Vì Δ>0 nên phương trình có hai nghiệm phân biệt là:
\(\left\{{}\begin{matrix}x_1=\dfrac{14-2\sqrt{205}}{-24}=\dfrac{-7+\sqrt{205}}{12}\\x_2=\dfrac{14+2\sqrt{2015}}{-24}=\dfrac{-7-\sqrt{205}}{12}\end{matrix}\right.\)
b) Ta có: \(\dfrac{3}{35}-\left(\dfrac{3}{5}-x\right)=\dfrac{2}{7}\)
\(\Leftrightarrow\dfrac{3}{5}-x=\dfrac{3}{35}-\dfrac{10}{35}=\dfrac{-7}{35}=\dfrac{-1}{5}\)
hay \(x=\dfrac{3}{5}-\dfrac{-1}{5}=\dfrac{3}{5}+\dfrac{1}{5}=\dfrac{4}{5}\)
Bài 3:
a) Ta có: \(2x-3=x+\dfrac{1}{2}\)
\(\Leftrightarrow2x-x=\dfrac{1}{2}+3\)
\(\Leftrightarrow x=\dfrac{7}{2}\)
b) Ta có: \(4x-\left(x+\dfrac{1}{2}\right)=2x-\left(\dfrac{1}{2}-5\right)\)
\(\Leftrightarrow3x-\dfrac{1}{2}-2x+\dfrac{1}{2}-5=0\)
\(\Leftrightarrow x=5\)
Tìm x biết
a, 5x-5^2=10
b, 9x-2:3^2=3^4
c, 10x+2^2 nhân 5 = 10^2
b) \(9x-2:3^2=3^4\)
\(9x-2:9=81\)
\(2:9=9x-81\)
\(\dfrac{2}{9}=9x-81\)
\(9x=81+\dfrac{2}{9}\)
\(9x=\dfrac{731}{9}\)
\(x=\dfrac{731}{9}:9\)
\(x=\dfrac{731}{81}\)
\(a.5x-5^2=10\) \(b.9x-2:3^2=3^4\)
\(5x=10+5^2\) \(9x-2=3^4.3^2\)
\(5x=35\) \(9x-2=729\)
\(x=35:5=7\) \(9x=729+2=731\)
\(x=731:9\)
\(x=\dfrac{731}{81}\)
\(c=10x+\left(2^2\right).5=10^2\)
\(10x+20=100\)
\(10x=100-20\)
\(10x=80\)
\(x=80:10=8\)
a) \(5x-5^2=10\)
\(=5x-25=10\)
\(5x=10+25\)
\(5x=35\)
\(x=35:5\)
\(x=7\)
giúp mk vs :(( ( tìm x )
\(\dfrac{-4}{x}=\dfrac{x}{-49}\); \(\dfrac{3.5}{x-3}=\dfrac{5}{3}\)
(2x + 1) : 2 = 12 : 3 ; ( 2x - 14 ): 3= 12 :9
giúp mk nhaa vội lém á :((
\(\dfrac{-4}{x}=\dfrac{x}{-49}\\ \Rightarrow x^2=\left(-4\right)\left(-49\right)\\ \Rightarrow x^2=196\\ \Rightarrow x=\pm14\)
\(\dfrac{3.6}{x-3}=\dfrac{5}{3}\\ \Rightarrow5\left(x-3\right)=3.3.6\\ \Rightarrow5\left(x-3\right)=54\\ \Rightarrow x-3=\dfrac{54}{5}\\ \Rightarrow x=\dfrac{54}{5}+3\\ \Rightarrow x=\dfrac{69}{15}\)
\(\left(2x+1\right):2=12:3\\ \left(2x+1\right):2=4\\2x+1=2\\ 2x=1\\ x=\dfrac{1}{2} \)
\(\left(2x-14\right):3=12:9\\ \left(2x-14\right):3=\dfrac{4}{3}\\ 2x-14=4\\ 2x=16\\ x=8\)
Tìm x, y ∈ Z biết
a) (x + 1)(y – 2) = 0
b) (x – 5)(y – 7) = 1
c) (x + 4)(y – 2) = 2
d) (x + 3)(y – 6) = -4
e) (x + 7)(5 – y) = -6
f) (12 – x)(6 – y) = -2
mk cần gấp, giúp với nhé, mk sẽ tick cho ai làm sớm ^^
Giúp mk với
Tìm |x|, biết
a)x=2/7 b)x=\(\dfrac{-5}{6}\) c)x=\(4\dfrac{2}{3}\) d)x=-3,41
a) \(\left|\dfrac{2}{7}\right|\) = \(\dfrac{2}{7}\)
b) \(\left|\dfrac{-5}{6}\right|\) = \(\dfrac{5}{6}\)
c) \(\left|4\dfrac{2}{3}\right|\) = \(4\dfrac{2}{3}\)
d) \(\left|-3,41\right|\) = \(3,41\)
a) \(\left|x\right|=\dfrac{2}{7}\)
b) \(\left|x\right|=\dfrac{5}{6}\)
c) \(\left|x\right|=4\dfrac{2}{3}\)
d) \(\left|x\right|=3.41\)