Nếu x ≥ 2 , ta có :
- Với x ≠ 2 , ta có :
3.(x - 2) + (4x - 8) = 2 - 1/3
3x - 6 + 4x - 8 = 5/3
7x - 14=5/3
⇒ x = 47/3 : 7 = 47/21
Với x = 2, ta có :
3.(2 - 2) + (4.2 - 8) = 2 - 1/3
⇒ 0 = 5/3 (vô lí)
Nếu x < 2 , ta có :
3.[-(x - 2)] + -(4x - 8) = 2 - 1/3
-3x + 6 - 4x + 8 = 5/3
14 - 7x = 5/3
⇒ x = 37/3 : 7 = 37/21
Vậy x = 47/21 hoặc x = 37/21
Câu 1: Tinh
\(A=\left(\dfrac{3}{5}\right)^2.5^2-\left(2\dfrac{1}{4}\right)^3:\left(\dfrac{3}{4}\right)^3+\dfrac{1}{2}\)
\(B=\left[\dfrac{4}{11}.\left(\dfrac{1}{25}\right)^0+\dfrac{7}{22}.2\right]^{2010}-\left(\dfrac{1}{2^2}:\dfrac{8^2}{4^4}\right)^{2009}\)
\(\dfrac{7}{8}.\left(\dfrac{2}{12}+\dfrac{4}{10}\right)\)
\(\dfrac{3}{2}-\dfrac{5}{6}:\left(\dfrac{1}{2}\right)^2+\sqrt{4}\)
Câu 2: Tim x
\(2.x-\dfrac{5}{4}=\dfrac{20}{15}\)
\(\left(x+\dfrac{1}{3}\right)^3=\left(\dfrac{-1}{8}\right)\)
\(a.\left|x+2\right|+\left|x-1\right|=3-\left(y+2\right)^2\)
\(b.\left|x-5\right|+\left|1-x\right|=\dfrac{12}{\left|y+1\right|+3}\)
\(c.\left|y+3\right|+5=\dfrac{10}{\left(2x-6\right)^2+2}\)
\(d.\left|x-1\right|+\left|3-x\right|=\dfrac{6}{\left|y-3\right|+3}\)
1/ Tìm GTNN:
a,\(\left|7x-5y\right|+\left|2z-3y\right|+\left|xy+yz+xz-2000\right|\)
b,\(\left|3x-7\right|+\left|3x+2\right|+8\)
2/ Tìm x, y:
a, \(\left|x-5\right|+\left|1-x\right|=\dfrac{12}{\left|y+1\right|+3}\)
b,\(\left|y+3\right|+5=\dfrac{10}{\left(2x-6\right)^2+2}\)
c,\(\left|x-1\right|+\left|3-x\right|=\dfrac{6}{\left|y+3\right|+3}\)
Bài 4 : Tìm x,y biết :
a)\(3\dfrac{1}{4}-\dfrac{1}{4}\left|x-0,25\right|=\dfrac{1}{4}\)
b)\(\left|x-3\right|=-4\)
c)\(\left|x-\dfrac{1}{2}\right|+1=0\)
d)\(\left|x-\dfrac{1}{5}\right|=\left|\dfrac{3}{4}-2x\right|\)
e)\(\left|x+2\right|3=0\)
f)\(\left|2x-1\right|-\left|x+2\right|=0\)
g)\(\left|x+2\right|+\left|y-1\right|=0\)
h)\(\left|2x\right|+\left|y+\dfrac{1}{4}\right|=0\)
Tìm x, biết \(\left|x+\dfrac{7}{9}\right|+\left|x+\dfrac{1}{3}\right|+\left|x+2\dfrac{8}{9}\right|=5x\)
tìm giá trị lớn nhất của các biểu thức
\(A=5-3\left(2x-1\right)^2\) \(B=\dfrac{1}{2\cdot\left(x-1\right)^2+3}\) \(C=\dfrac{x^2+8}{x^2+2}\) \(D=\dfrac{1}{\sqrt{x}+3}\)
Tìm x biết: \(\left|x-\dfrac{1}{3}\right|\)+\(\dfrac{4}{5}\)\(=\left|-3,2+\dfrac{2}{5}\right|\)
\(\left|x+\dfrac{1}{101}\right|+\left|x+\dfrac{2}{101}\right|+\left|x+\dfrac{3}{101}\right|+...+\left|x+\dfrac{100}{101}\right|=101x\)
Tìm x,y biết :
a ) \(1-\left|x-\dfrac{1}{4}\right|=0,25\)
b)\(\left|x+0,5\right|+2,25=0,5\)
c)\(\left|2x+5\right|=\left|1-x\right|\)
d)\(\left|x-2\right|-0,5=\dfrac{1}{4}\)
e)\(\left|\dfrac{3}{2}-x\right|+2=2\)
f)\(\left|x-3\right|+5=4\)
g)\(\left|\dfrac{1}{2}x-3\right|+\left|y+0,5\right|=0\)
h)\(\left|x+4\right|+\left|1-2y\right|=0\)
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