Nếu `sqrt(x-3) in I -> A in I ->` Vô lý.
`-> sqrt(x-3) in ZZ`.
`-> 5 vdots sqrt(x-3)`
`-> sqrt(x-3) in Ư(5)`.
`-> x in {4, 7, 28}`.
1. Tìm x, biết : \(\sqrt{x^2}=0\)
2. Tính :
\(A=\left(0,75-0,6+\dfrac{3}{7}+\dfrac{3}{13}\right).\)\(\left(\dfrac{11}{7}+\dfrac{11}{3}+2,75-2,2\right)\)
\(B=\dfrac{\left(1+2+3+...+100\right)\left(\dfrac{1}{2}-\dfrac{1}{3}-\dfrac{1}{7}-\dfrac{1}{9}\right)\left(63.1,2-21.3,6\right)}{1-2+3-4+...+99-100}\)
\(C=\left|\dfrac{4}{9}-\left(\dfrac{\sqrt{2}}{2}\right)^2\right|+\left|0,4+\dfrac{\dfrac{1}{3}-\dfrac{2}{5}-\dfrac{3}{7}}{\dfrac{2}{3}-\dfrac{4}{5}-\dfrac{6}{7}}\right|\)
Help me !!! Nhanh lên nha chiều mk phải nộp rồi
bài 1: tính
a) 3/4+(-5/2)+(-3/5)
b) \(\sqrt{\left(7\right)^2}+\sqrt{\dfrac{25}{16}-\dfrac{3}{2}}\)
c)\(\dfrac{1}{2}.\sqrt{100}-\sqrt{\dfrac{1}{16}+\left(\dfrac{1}{3}\right)^0}\)
Bài 1 : Kí hiệu [x] là số nguyên lớn nhất không vượt qua x. Tìm [x] biết :
a) x = \(\sqrt{2+\sqrt{2+\sqrt{2+...+\sqrt{2}}}}\) ( n dấu căn )
b) x = \(\left[\sqrt{1}\right]+\left[\sqrt{2}\right]+\left[\sqrt{3}\right]+...+\left[\sqrt{100}\right]\)
Bài 2 : Tìm x để A có giá trị nguyên:
a) A = \(\dfrac{\sqrt{x}-1}{\sqrt{x}+1}\)
b) A = \(\dfrac{\sqrt{x}+3}{2\sqrt{x}+1}\)
c) A = \(\dfrac{\sqrt{x}+1}{\sqrt{x}-1}\) với \(x\) thuộc Z
giúp mình với
1, tính
a, \(7\times\sqrt{\dfrac{6^2}{7^2}}-\sqrt{25}+\sqrt{\dfrac{\left(-3\right)^2}{2}}\)
b, \(-\sqrt{\dfrac{64}{49}}-\dfrac{3}{5}\times\sqrt{\dfrac{25}{64}}+\sqrt{0,25}\)
c, \(\sqrt{\dfrac{10000}{5}}-\dfrac{1}{4}.\sqrt{\dfrac{16}{9}}+\sqrt{\dfrac{\left(-3\right)^2}{\left(4\right)}}\)
d, \(\left|\dfrac{1}{4}-\sqrt{0,0144}\right|-\dfrac{3}{2}+\sqrt{\dfrac{81}{169}}\)
\(\left(\sqrt{\dfrac{1}{4}-1,2}\right):1\dfrac{1}{20}-\left(-\dfrac{5}{2}\right)^2+\left|1,25-\dfrac{3}{4}\right|\)
Thực hiện phép tính
\(M=\left(18\dfrac{1}{3}:\sqrt{225}+8\dfrac{2}{3}.\sqrt{\dfrac{49}{4}}\right):\left[\left(12\dfrac{1}{3}+8\dfrac{6}{7}\right)-\dfrac{\left(\sqrt{7}\right)^2}{\left(3\sqrt{2}\right)^2}\right]:\dfrac{1704}{445}\)
1) Chứng minh rằng : \(\dfrac{1}{\sqrt{1}}+\dfrac{1}{\sqrt{2}}+\dfrac{1}{\sqrt{3}}+...+\dfrac{1}{\sqrt{100}}>10\)
2) Tìm x,y để : \(C=-18-\left|2x-6\right|-\left|3y+9\right|\)đạt giá trị lớn nhất .
Helppp Meeee!!! Mơn trc ạ !!! <3
Tìm x biết:
a)\(\sqrt{x}=4\)
b)\(\sqrt{x-2}=3\)
c)\(\sqrt{\dfrac{x}{3}-\dfrac{7}{6}}=\dfrac{1}{6}\)
d)\(x^2=7v\text{ới}x< 0\)
e)\(x^2-4=0v\text{ới}x>0\)
f)\(\left(2x+7\sqrt{7}\right)^2=7\)
Rút gọn A= \(1-\dfrac{5}{\sqrt{196}}-\dfrac{5}{\left(2.\sqrt{21}\right)^2}-\dfrac{\sqrt{25}}{204}-\dfrac{\left(\sqrt{5}\right)^2}{374}\)
Tính:
a) \(2\sqrt{a^2}\left(a\ge0\right)\)
b) \(\sqrt{3a^2}\left(a< 0\right)\)
c) \(5\sqrt{a^4}\left(a< 0\right)\)
d) \(\dfrac{1}{3}\sqrt{c^6}\left(c< 0\right)\)
