đang cần gấp chìu nộp cho cô òi ( ai nhanh + đúng = 20 ticks
bài 1 tính
4.\(\left(\frac{-1}{2}\right)^3-2.\left(\frac{-1}{2}\right)^2+3.\left(\frac{-1}{2}\right)+1\)1
bài 2 : tìm x
a)\(\frac{37-x}{x+13}=\frac{3}{7}\)
b) | x - \(\frac{1}{2}\)| - \(\sqrt{\frac{1}{9}}=\sqrt{\frac{1}{4}}\)
c) \(2^{3x+2}=4^{x+5}\)
d) \(\frac{3^2.3^8}{27^3}=3^x\)
bài 3: tìm x,y
a)\(\frac{2x}{3y}=-\frac{1}{3}\)và -2x+3y=7
Bài 1:
\(4.\left(\frac{-1}{2}\right)^2-2.\left(\frac{-1}{2}\right)^2+3.\left(\frac{-1}{2}\right)+1\)
\(=4.\frac{1}{4}-2.\frac{1}{4}+3.\left(\frac{-1}{2}\right)+1\)
\(=1-\frac{1}{2}-\frac{3}{2}+1\)
\(=0\)
Bài 2:
a) \(\frac{37-x}{x+13}=\frac{3}{7}\)
\(\Rightarrow7\left(37-x\right)=3\left(x+13\right)\)
\(\Rightarrow259-7x=3x+39\)
\(\Rightarrow259-39=3x+7x\)
\(\Rightarrow220=10x\)
\(\Rightarrow x=22\)
d) \(\frac{3^2.3^8}{27^3}=3^x\)
\(\Rightarrow\frac{3^{10}}{\left(3^3\right)^3}=3^x\)
\(\frac{\Rightarrow3^{10}}{3^9}=3^x\)
\(\Rightarrow3=3^x\)
\(\Rightarrow x=1\)
Hok tốt nha^^
Bài 2:
a) \(\frac{37-x}{x+13}=\frac{3}{7}\)
\(\left(37-x\right).7=3\left(x+13\right)\)
\(259-7x=3x+39\)
\(259=3x+39+7x\)
\(259=10x+39\)
\(259-39=10x\)
\(220=10x\)
\(x=22\)
b) \(\left|x-\frac{1}{2}\right|-\sqrt{\frac{1}{9}}=\sqrt{\frac{1}{4}}\)
\(\left|x-\frac{1}{2}\right|-\frac{1}{3}=\frac{1}{2}\)
\(\left|x-\frac{1}{2}\right|=\frac{1}{2}+\frac{1}{3}\)
\(\left|x-\frac{1}{2}\right|=\frac{5}{6}\)
\(\orbr{\begin{cases}x-\frac{1}{2}=\frac{5}{6}\\x-\frac{1}{2}=-\frac{5}{6}\end{cases}}\)
\(\orbr{\begin{cases}x=\frac{4}{3}\\x=-\frac{1}{3}\end{cases}}\)
c) \(2^{3x+2}=4^{x+5}\)
\(2^{3x+2}=2^{2\left(x+5\right)}\)
\(3x+2=2\left(x+5\right)\)
\(3x+2=2x+10\)
\(3x=2x+10-2\)
\(3x=2x+8\)
\(3x-2x=8\)
\(x=8\)
