\(4^x-10\times2^x+16=0\)
\(4^x-10\times2^x+16=0\)
\(4^x-10.2^x+16=0\)
\(\Leftrightarrow\left(2^x\right)^2-10.2^x+16=0\)
Đặt 2x = t
\(\Rightarrow t^2-10t+16=0\)
\(\Leftrightarrow t^2-2t-8t+16=0\)
\(\Leftrightarrow t\left(t-2\right)-8\left(t-2\right)=0\)
\(\Leftrightarrow\left(t-2\right)\left(t-8\right)=0\)
\(\Rightarrow\left\{{}\begin{matrix}t=2\\t=8\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}2^x=2\\2^x=8\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}x=1\\x=3\end{matrix}\right.\)
\(4^x-10\times2^x+16=0\)
\(4^x-10\times2^x+16=0\)
\(\Leftrightarrow2^{2x}-2\times5\times2^x+16=0\)
\(\Leftrightarrow\left[\left(2^x\right)^2-2\times2^x\times5+25\right]-9=0\)
\(\Leftrightarrow\left(2^x-5\right)^2-3^2=0\)
\(\Leftrightarrow\left(2^x-5-3\right)\left(2^x-5+3\right)=0\)
\(\Leftrightarrow\left(2^x-8\right)\left(2^x-2\right)=0\)
\(\Leftrightarrow2^x-8=0\) hoặc \(2^x-2=0\)
\(\cdot2^x-8=0\Leftrightarrow2^x=8\Leftrightarrow x=3\)
\(\cdot2^x-2=0\Leftrightarrow2^x=2\Leftrightarrow x=1\)
Vậy \(S=\left\{3;1\right\}\)
\(4^x-10\cdot2^x+16=0\)
\(=\left(2^x\right)^2-10\cdot2^x+16=0\)
Đặt \(t=2^x\). Ta có:
\(t^2-10t+16=0\)
\(\Rightarrow t^2-2\cdot t\cdot5+25-9=0\)
\(\Rightarrow\left(t-5\right)^2-3^2=0\)
\(\Rightarrow\left(t-8\right)\left(t-2\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}t=8\\t=2\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}x=3\\x=1\end{matrix}\right.\)
Vậy S = {1,3}
\(4^x-10.2^x+16=0\)
\(\Leftrightarrow\left(2^x\right)^2-10.2^x=-16\)
\(\Leftrightarrow\left[{}\begin{matrix}2^x\left(2^x-10\right)=2\left(2-10\right)\Leftrightarrow2^x=1\Leftrightarrow2^x=2^0\Leftrightarrow x=0\\2^x\left(2^x-10\right)=8\left(8-10\right)\Leftrightarrow2^x=8\Leftrightarrow2^x=2^3\Leftrightarrow x=3\end{matrix}\right.\)
Vậy \(x\in\left\{0;3\right\}\)
1. Tìm x biết:
\(\left(3\times x-15\right)^7=0\)
\(10-\left\{\left[\left(x:3+17\right):10+3\times2^4\right]:10\right\}=5\)
Giúp mik với mọi người ơi !!!!
a ) \(\left(3\times x-15\right)^7=0.\)
\(3\times x-15=0\)
\(3\times x=15\)
\(x=5\)
b ) \(10-\left\{\left[\left(x\div3+17\right)\div10+3\times2^4\right]\div10\right\}=5\)
\(10-\left\{\left[\left(x\div3+17\right)\div10+3\times16\right]\div10\right\}=5\)
\(10-\left\{\left[\left(x\div3+17\right)\div10+48\right]\div10\right\}=5\)
\(\left[\left(x\div3+17\right)\div10+48\right]\div10=10-5\)
\(\left[\left(x\div3+17\right)\div10+48\right]\div10=5\)
\(\left(x\div3+17\right)\div10+48=50\)
\(\left(x\div3+17\right)\div10=2\)
\(x\div3+17=20\)
\(x\div3=3\)
\(x=9\)
tìm số nguyên x biết
\(2\times2^2\times2^3\times2^4\times...\times2^x=1024\)
\(2.2^2.2^3.2^4....2^x=1024=2^{10}\)
\(\Rightarrow2^{1+2+3+\text{4+}...+x}=2^{10}\)
\(\Rightarrow1+2+3+4+...+x=10\)
\(\Rightarrow1+2+3+4+...x=1+2+3+4\)=>x=4
tìm x , biết
\(a,(x-\frac{1}{2})\times2=\frac{9}{16}\)
\(b,|x+\frac{1}{2}|=\frac{3}{4}\)
a) (x - 1/2) x 2 = 9/16
=> x - 1/2 = 9/16 : 2
=> x - 1/2 = 9/16 x 1/2
=> x - 1/2 =9/32
=> x = 9/32 + 1/2
=> x = 25/32
b) |x + 1/2| = 3/4
=> x + 1/2 = 3/4 hoặc x + 1/2 =-3/4
=>x = 3/4 - 1/2 hoặc x = -3/4 -1/2
=>x = 1/4 hoặc x = -5/4
Vậy .........
Tìm x \(\in N\) , biết :
\(2^x\times2^{x+1}\times2^{x+2}\le1000...0:25^9\)
( số 1000...0 có 18 chữ số 0 )
2x.2x + 1.2x + 2 \(\le\) 1000...00 : 259
<=> 2x + x + 1 + x + 2 \(\le\) 1009 : 259
<=> 23x + 3 \(\le\) 49
<=> 23x + 3 \(\le\) 218
<=> 3x + 3 \(\le\) 18
<=> x \(\le\) 5
Mà x \(\in\) N => x \(\in\) {0; 1; 2; 3; 4; 5}
Tính giá trị của mỗi phân số sau:
\(E=\dfrac{11\times3^{29}-\left(3^2\right)^{15}}{2\times3^{14}\times2\times3^{14}}\)
\(G=\dfrac{5\times3^{11}+4\times3^{12}}{3^9\times5^2-3^0\times2^3}\)
\(H=\dfrac{\left(3\times4\times2^{16}\right)^2}{11\times2^{13}\times4^{11}-16^9}\)
\(E=\dfrac{11.3^{29}-3^{2^{15}}}{2.3^{14}.2.3^{14}}\)
\(=\dfrac{11.3-3^{30}}{2^2}=\dfrac{33-3^{30}}{4}\)
Tìm số nguyên x, biết:
\(2\times2^2\times2^3\times2^4\times.........\times2^x=1024\)
Giúp mình zới, mình đang cần gấp, cảm ơn!
Cho B=\(2\times2^2+3\times2^3+4\times2^4+5\times2^5+...+10\times2^{10}\)
So sánh B và \(2^{14}\)