tìm x biết :
I X-2 I = 3X +7
NHANH LÊN TK CHO !
Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
b2 = ac
\(\Rightarrow\frac{a}{b}=\frac{b}{c}\)
\(\Rightarrow\frac{a^2}{b^2}=\frac{b^2}{c^2}=\frac{a}{b}.\frac{b}{c}=\frac{a}{c}\)
\(\Rightarrow\frac{a^2+b^2}{b^2+c^2}=\frac{a}{c}\)
CMR nếu a2 = b.c thì
a,\(\frac{a+b}{a-b}=\frac{c+a}{c-a}\) b,\(\frac{a^2+c^2}{b^2+a^2}=\frac{c}{b}\)
a) a2 = bc
\(\Rightarrow\frac{a}{c}=\frac{b}{a}\)
\(\Rightarrow\frac{a}{c}=\frac{b}{a}=\frac{a+b}{c+a}=\frac{a-b}{c-a}\)
\(\Rightarrow\frac{a+b}{a-b}=\frac{c+a}{c-a}\)
b) a2 = bc
\(\Rightarrow\frac{a}{b}=\frac{c}{a}\)
\(\Rightarrow\frac{a^2}{b^2}=\frac{c^2}{a^2}=\frac{a}{b}.\frac{c}{a}=\frac{c}{b}\)
\(\Rightarrow\frac{a^2+c^2}{b^2+a^2}=\frac{c}{b}\)
(x-1/2)^3=27
(x-1/2)^3=3^3
suy ra:x-1/2=3
x=3+1/2
x=7/2
vậy x=7/2
\(\frac{x}{6}+\frac{7}{3.2^2}=\frac{17}{18}-\frac{1}{3^2}\)
\(\frac{x}{6}+\frac{7}{12}=\frac{5}{6}\)
\(\frac{x}{6}=\frac{5}{6}-\frac{7}{12}\)
\(\frac{x}{6}=\frac{1}{4}\)
\(x=\frac{1}{4}.6\)
\(x=\frac{3}{2}\)
\(\frac{a}{3}\)=\(\frac{a^2}{9}\) \(\frac{b}{7}\)= \(\frac{c}{5}\) và \(a^2\)+ \(b^2\)+ \(c^2\)= -60
\(\Rightarrow\)\(\frac{a^2}{3^2}\)= \(\frac{b^2}{7^2}\)= \(\frac{c^2}{5^2}\) và \(a^2\)+ \(b^2\)+ \(c^2\)=-60
\(\Rightarrow\)\(\frac{a^2}{9}\)= \(\frac{b^2}{49}\)= \(\frac{c^2}{25}\) và \(a^2\)+ \(b^2\)+ \(c^2\)=-60
\(\Rightarrow\)\(\frac{a^2+b^2+c^2}{9+49+25}\)= \(\frac{-60}{83}\)
Suy ra: \(\frac{a^2}{9}\)=\(\frac{-60}{83}\)= \(\frac{-540}{83}\)
\(\frac{b^2}{49}\)= \(\frac{-60}{83}\)= \(\frac{-2940}{83}\)
\(\frac{c^2}{25}\)= \(\frac{-60}{83}\)= \(\frac{-1500}{83}\)
| x - 2 | = 3x + 7
\(\Rightarrow\orbr{\begin{cases}x-2=3x+7\\x-2=-\left(3x+7\right)\end{cases}}\)
\(\Rightarrow\orbr{\begin{cases}x-2=3x+7\\x-2=-3x-7\end{cases}}\)
\(\Rightarrow\orbr{\begin{cases}x-3x=7+2\\x+3x=-7+2\end{cases}}\)
\(\Rightarrow\orbr{\begin{cases}-2x=9\\4x=-5\end{cases}}\)
\(\Rightarrow\orbr{\begin{cases}x=\frac{-9}{2}\\x=\frac{-5}{4}\end{cases}}\)