tim x
1/8*16^x=2^x
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TH1: TH2:
-8(x-3)=24-16:2 -8(-x+3)=24-16:2
-8x+24=16 8x-24=16
-8x=16-24 8x=16+24
-8x=-8 8x=40
x=1 x=5
Vậy \(x\in1;5\)
-8/x-3/=24-16:2 Suy ra x-3=-8;8
-8/x-3/=24-8 x=11;-5
-8/x-3/=16
/x-3/=16+(-8)
/x-3/=8
\(A=\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+\frac{1}{16}+\frac{1}{32}+\frac{1}{64}+\frac{1}{128}\)
\(2\times A=1+\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+\frac{1}{16}+\frac{1}{32}+\frac{1}{64}\)
\(2\times A-A=\left(1+\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+\frac{1}{16}+\frac{1}{32}+\frac{1}{64}\right)-\left(\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+\frac{1}{16}+\frac{1}{32}+\frac{1}{64}+\frac{1}{128}\right)\)
\(A=1-\frac{1}{128}\)
\(A=\frac{127}{128}\)
\(B=\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+\frac{1}{16}\)
\(2\times B=1+\frac{1}{2}+\frac{1}{4}+\frac{1}{8}\)
\(B=1-\frac{1}{16}=\frac{15}{16}\)
\(\left(x+\frac{1}{2}\right)+\left(x+\frac{1}{4}\right)+\left(x+\frac{1}{8}\right)+\left(x+\frac{1}{16}\right)=1\)
\(\Leftrightarrow4\times x+\frac{15}{16}=1\)
\(\Leftrightarrow4\times x=\frac{1}{16}\)
\(\Leftrightarrow x=\frac{1}{64}\)
x,y là hai đại lượng tỉ lệ thuận
=>\(\dfrac{x_1}{x_2}=\dfrac{y_1}{y_2}\)
=>\(\dfrac{x_1}{4}=\dfrac{y_1}{16}\)
=>\(\dfrac{x_1}{1}=\dfrac{y_1}{4}\)
mà \(3x_1+2y_1=22\)
nên Áp dụng tính chất của dãy tỉ số bằng nhau, ta được:
\(\dfrac{x_1}{1}=\dfrac{y_1}{4}=\dfrac{3x_1+2y_1}{3\cdot1+2\cdot4}=\dfrac{22}{11}=2\)
=>\(x_1=2\cdot1=2\)
=>Chọn D
x . 4 + 15/16 = 1
x . 4 = 1 – 15/16 = 1/16
x = 1/16 : 4 = 1/64
\(\Leftrightarrow\left(\dfrac{3}{4}\right)^x.\left(\dfrac{4}{3}\right)^{\dfrac{4}{x}}=\dfrac{9}{16}\)
\(\Rightarrow\left(\dfrac{3}{4}\right)^x.\left(\dfrac{3}{4}\right)^{-\dfrac{4}{x}}=\left(\dfrac{3}{4}\right)^2\)
\(\Rightarrow\left(\dfrac{3}{4}\right)^{x-\dfrac{4}{x}}=\left(\dfrac{3}{4}\right)^2\)
\(\Rightarrow x-\dfrac{4}{x}=2\)
\(\Rightarrow x^2-2x-4=0\)
Viet: \(x_1+x_2=2\)
1/8*16^x=2^x
1/8=2^x/16^x
(2/16)^x=1/8
(1/8)^x=1/8
suy ra x=1
Vậy x=1
\(\frac{1}{8}\cdot16^x=2^x\)
\(\Leftrightarrow\frac{1}{8}=\frac{2^x}{16^x}\)
\(\Leftrightarrow\left(\frac{2}{16}\right)^x=\frac{1}{8}\)
\(\Leftrightarrow\left(\frac{1}{8}\right)^x=\frac{1}{8}\)
Suy ra x=1