tìm x, biết
x : 15 = 8 : 24
Tìm x biết
x-11/13=15/13
\(x=\dfrac{15}{13}+\dfrac{11}{13}=\dfrac{15+11}{13}=\dfrac{26}{13}\)
\(x=\dfrac{15}{13}+\dfrac{11}{13}\\ x=\dfrac{26}{13}\)
Tìm số nguyên x biết
x-1/8= 4/x-2
\(x-\dfrac{1}{8}=\dfrac{4}{x-2}\) hay \(x-\dfrac{1}{8}=\dfrac{4}{x}-2\) vậy bạn?
\(\dfrac{x-1}{8}=\dfrac{4}{x-2}\)
=>\(\dfrac{\left(x-1\right)\left(x-2\right)}{8.\left(x-2\right)}=\dfrac{4.8}{\left(x-2\right).8}\)
=>khử mẫu
=>(x-1)(x-2)=32
.......
Tìm x biết
x^2-3x^2+3x-1=-8
\(x^3-3x^2+3x-1=-8\)
\(\Leftrightarrow x-1=-2\)
hay x=-1
tìm x biết
x-3=(3-x)^2
x^3+3/2x^2+3/4x+1/8=1/64
\(\left(x-3\right)=\left(3-x\right)^2\)
\(\Leftrightarrow x-3=\left(x-3\right)^2\)
\(\Leftrightarrow\left(x-3\right)-\left(x-3\right)^2=0\)
\(\Leftrightarrow\left(x-3\right)\left[1-\left(x-3\right)\right]=0\)
\(\Leftrightarrow\left(x-3\right)\left(4-x\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x-3=0\\4-x=0\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=3\\x=4\end{matrix}\right.\)
___________
\(x^3+\dfrac{3}{2}x^2+\dfrac{3}{4}x+\dfrac{1}{8}=\dfrac{1}{64}\)
\(\Leftrightarrow x^3+3\cdot\dfrac{1}{2}\cdot x^2+3\cdot\left(\dfrac{1}{2}\right)^2\cdot x+\left(\dfrac{1}{2}\right)^3=\dfrac{1}{64}\)
\(\Leftrightarrow\left(x+\dfrac{1}{2}\right)^3=\left(\dfrac{1}{4}\right)^3\)
\(\Leftrightarrow x+\dfrac{1}{2}=\dfrac{1}{4}\)
\(\Leftrightarrow x=\dfrac{1}{4}-\dfrac{1}{2}\)
\(\Leftrightarrow x=-\dfrac{1}{4}\)
tìm x thuộc n, biết
x mũ 20=x
\(x^{20}=x\)
⇒\(x^{20}-x=0\)
⇒\(x\left(x^{19}-1\right)=0\)
⇔\(x^{19}-1=0\) hoặc x=0
⇔x=1 hoặc x=0
\(x^{20}=x\\ \Leftrightarrow x^{20}-x=0\\ \Leftrightarrow x\left(x^{19}-1\right)=0\\ \Leftrightarrow\left[{}\begin{matrix}x=0\\x=1\end{matrix}\right.\)
\(x^{20}=x\\ \Rightarrow x\in\left\{0;1\right\}\)vì \(x\in N\)
Tìm x, biết
x×2,5 + 7,5 = 36,5
X × 2,5 + 7,5 = 36,5
X × 2,5 = 36,5 - 7,5
X × 2,5 = 29
X = 29 : 2,5
X = 11,6
\(x\times2,5+7,5=36,5\\ x\times2,5=36,5-7,5\\ x\times2,5=29\\ x=29:2,5\\ x=11,6\)
Tìm x, biết
x+ 1538 = 3215
x- 215 = 1578
345- x =182
\(x+1538=3215\\ \Rightarrow x=3215-1538=1677\\ x-215=1578\\ \Rightarrow x=1578+215=1793\\ 345-x=182\\ \Rightarrow x=345-182=163\)
x+1538=3215⇒x=3215−1538=1677x−215=1578⇒x=1578+215=1793345−x=182⇒x=345−182=163
x+1538=3215⇒x=3215−1538=1677x−215=1578⇒x=1578+215=1793345−x=182⇒x=345−182=163
Tìm X biết
X^2/20 = 4/5
\(\dfrac{x^2}{20}=\dfrac{4}{5}\)
\(\Leftrightarrow x^2=16\)
hay \(x\in\left\{4;-4\right\}\)
tìm x thuộc Z biếtx-(-25-17-x)=6+x