Tìm x biết:
x(x+5)(x-5)-(x+2)(x^2-2x+4)=42
Tìm x biết:
x.(x-5).(x+5)-(x+2).(x2-2x+4)=17
Giải chi tiết giúp mình nha.Cảm ơn.
\(x\left(x-5\right)\left(x+5\right)-\left(x+2\right)\left(x^2-2x+4\right)=17\)
\(\Rightarrow x\left(x^2-25\right)-\left(x^3+8\right)=17\)
\(\Rightarrow x^3-25x-x^3-8=17\)
\(\Rightarrow25x=-25\Rightarrow x=-1\)
tìm x,y biết:
x/-5=y/4=2
x/3=2/y;x,y ∈ Z
a, Xét \(\dfrac{x}{-5}=2\Rightarrow x=-10\)
\(\dfrac{y}{4}=2\Leftrightarrow y=8\)
b, \(xy=6\Rightarrow x;y\inƯ\left(6\right)=\left\{\pm1;\pm2;\pm3;\pm6\right\}\)
x | 1 | -1 | 2 | -2 | 3 | -3 | 6 | -6 |
y | 6 | -6 | 3 | -3 | 2 | -2 | 1 | -1 |
2.(x-5)-3.(x-4)=-6+15:9-3)
(x+7).(x-9)=0
/2x-5/-7=22
(/2x/-5)-7=22
tìm x,y thuộc z biết:x+y=x.y
a)tìm x,y biết:x-1/y+2 và x+y=23
b)tìm x biết: 4^5+4^5+4^5+4^5/3^5+3^5+3^5.6^5+6^5+6^5+6^5+6^5+6^5/2^5+2^5=8^2x-6
Theo đề ra, ta có: \(\frac{x-1}{y+2}=\frac{3}{5}\)
\(\Rightarrow\frac{x-1}{3}=\frac{y+2}{5}=\frac{x-1+y+2}{8}=\frac{23-1+2}{8}=\frac{24}{8}=3\)
\(\frac{x-1}{3}=3\Rightarrow x=3.3+1=10\)
\(\frac{y+2}{5}=3\Rightarrow y=5.3-2=13\)
tìm x biết:x(x^2-25)-(x+2)(x^2-2x+4)=3
tìm x biết:x+1/2+x+1/3+x+1/4+x+1/5=x+1/6
\(\Rightarrow x+\frac{1}{2}+x+\frac{1}{3}+x+\frac{1}{4}+x+\frac{1}{5}-x+\frac{1}{6}=0\)
\(\Rightarrow3x+\frac{1}{2}+\frac{1}{3}+\frac{1}{4}+\frac{1}{5}+\frac{1}{6}\)
k cho minh
\(x+\frac{1}{2}+x+\frac{1}{3}+x+\frac{1}{4}+x+\frac{1}{5}=x+\frac{1}{6}\)
\(\Leftrightarrow x+\frac{1}{2}+x+\frac{1}{3}+x+\frac{1}{4}+x+\frac{1}{5}-x-\frac{1}{6}=0\)
\(\Leftrightarrow3x+\frac{1}{2}+\frac{1}{3}+\frac{1}{4}+\frac{1}{5}-\frac{1}{6}=0\)
Tính ra nhé !
\(x+\frac{1}{2}+x+\frac{1}{3}+x+\frac{1}{4}+x+\frac{1}{5}=x+\frac{1}{6}\)
\(\left(x+x+x+x\right)+\left(\frac{1}{2}+\frac{1}{3}+\frac{1}{4}+\frac{1}{5}\right)=x+\frac{1}{6}\)
\(\Rightarrow4x+\frac{77}{60}=x+\frac{1}{6}\)
\(\Rightarrow3x=\frac{1}{6}-\frac{77}{60}\)
\(\Rightarrow3x=-\frac{67}{60}\)
\(\Rightarrow x=-\frac{67}{60}\div3=\frac{-67}{60.3}=-\frac{67}{180}\)
Vậy x = .........
Tìm x biết:x.(3x+2)+(x+1)^2-(2x-5)(2x+5)=-12
\(\text{x.(3x+2)+(x+1)^2-(2x-5)(2x+5)=-12}\\ \Leftrightarrow3x^2+2x+x^2+2x+1-4x^2+25=-12\\ \Leftrightarrow4x=-38\\ \Leftrightarrow x=-\dfrac{19}{2}\)
Tìm x,y biết:x/5=y/4 và x^2-y^2=1
dat \(\frac{x}{5}=\frac{y}{4}=k\)-> x=5k va y=4.k
thay x=5k va y=4k vao x2-y2=1 ta duoc
(5k)2-(4k)2=1
25k2-16k2=1
9k2=1
k2=\(\frac{1}{9}=\left(\frac{1}{3}\right)^2\)
-> k=1/3 hay k=-1/3
voi K=1/3--> x=5.1/3=5/3 va y=4.1/3=4/3
voi K=-1/3->x=5.-1/3=-5/3 va y=4.-1/3=-4/3