Tính:
B=[-\(\sqrt{2,25}\)+4\(\sqrt{\left(-2,15\right)^2}\)-(3\(\sqrt{\dfrac{7}{6}}\))2].\(\sqrt{1\dfrac{9}{16}}\)
C=\(3\dfrac{1}{2}\).\(\dfrac{4}{49}\)-[2,(4).\(2\dfrac{5}{11}\)]:(\(\dfrac{-42}{5}\))
Tính:
B=[-\(\sqrt{2,25}\)+4\(\sqrt{\left(-2,15\right)^2}\)-(3\(\sqrt{\dfrac{7}{6}}\))2].\(\sqrt{1\dfrac{9}{16}}\)
C=\(3\dfrac{1}{2}\).\(\dfrac{4}{49}\)-[2,(4).\(2\dfrac{5}{11}\)]:(\(\dfrac{-42}{5}\))
Tính:
C = \(3\dfrac{1}{2}.\dfrac{4}{49}-\left[2,\left(4\right).2\dfrac{5}{11}\right]:\left(\dfrac{-42}{5}\right)\)
= \(\dfrac{7}{2}.\dfrac{4}{49}-\left[\left(2+0,\left(1\right).4\right).\dfrac{27}{5}\right].\dfrac{-5}{42}\)
= \(\dfrac{1.2}{1.7}-\left[\left(2+\dfrac{1.4}{9}\right).\dfrac{27}{5}\right].\dfrac{-5}{42}\)
= \(\dfrac{2}{7}-\left[\dfrac{18+4}{9}.\dfrac{27}{5}\right].\dfrac{-5}{42}\)
= \(\dfrac{2}{7}-\left[\dfrac{22.9}{3.5}\right].\dfrac{-5}{42}\)
= \(\dfrac{2}{7}-\dfrac{198}{15}.\dfrac{-5}{42}=\dfrac{2}{7}-\dfrac{11}{3}.\dfrac{-1}{7}\)
= \(\dfrac{2}{7}+\dfrac{11}{21}\) = \(\dfrac{6+11}{21}\) = \(\dfrac{17}{21}\)
\(B=\left[-1.5+4\cdot2.15-9\cdot\dfrac{7}{6}\right]\cdot\dfrac{5}{4}\)
\(=-\dfrac{17}{5}\cdot\dfrac{5}{4}=-\dfrac{17}{4}\)
So sánh
\(\sqrt{8}-\sqrt{5}̀\) và 1
Ta có : \(1=3-2=\sqrt{9}-\sqrt{4}\)
Vì \(\left\{{}\begin{matrix}\sqrt{9}>\sqrt{8}\\\sqrt{4}< \sqrt{5}\end{matrix}\right.\Rightarrow}\left\{{}\sqrt{8}-\sqrt{5}< \sqrt{9}-\sqrt{4}=1}\)
các bạn ơi giúp mình bài toán này với:
em hãy viết các căn bậc 2 có thể chia hết cho 19
Các căn bậc có thể chia hết cho 19 là:
√361;√130321;√0;..........
Đúng nhớ tick nha!
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, \(\left|\dfrac{1}{4}-\sqrt{0,0144}\right|-\dfrac{3}{2}+\sqrt{\dfrac{81}{169}}\)
a: \(=7\cdot\dfrac{6}{7}-5+\dfrac{3\sqrt{2}}{2}=1+\dfrac{3}{2}\sqrt{2}\)
b: \(=-\dfrac{8}{7}-\dfrac{3}{5}\cdot\dfrac{5}{8}+\dfrac{1}{2}=\dfrac{-16+7}{14}-\dfrac{3}{8}=\dfrac{-9}{14}-\dfrac{3}{8}\)
\(=\dfrac{-72-42}{112}=\dfrac{-114}{112}=-\dfrac{57}{56}\)
c: \(=20\sqrt{5}-\dfrac{1}{4}\cdot\dfrac{4}{3}+\dfrac{3}{2}=20\sqrt{5}+\dfrac{3}{2}-\dfrac{1}{3}=20\sqrt{5}+\dfrac{7}{6}\)
1)\(\dfrac{2x+4}{7}\) = \(\dfrac{4x-2}{15}\) 4) \(\dfrac{6x-5}{-7}\) = \(\dfrac{5x-3}{-5}\)
2) \(\dfrac{2x+3}{6}\) = \(\dfrac{7x-3}{15}\) 5) \(\dfrac{12-7x}{-13}\) = \(\dfrac{4-3x}{-5}\)
3) \(\dfrac{11x-2}{7x+5}\) = \(\dfrac{11}{8}\)
\(1,\dfrac{2x+4}{7}=\dfrac{4x-2}{15}=\dfrac{2.\left(2x+4\right)}{2.7}=\dfrac{4x+8}{14}\)
Áp dụng tính chất của dãy tỉ số bằng nhau ta có :
\(\dfrac{2x+4}{7}=\dfrac{4x-2}{15}==\dfrac{4x+8}{14}=\dfrac{\left(4x+8\right)-\left(4x-2\right)}{14-15}=\dfrac{10}{-1}=-10\)
\(\Rightarrow\dfrac{2x+4}{7}=-10\)
\(\Rightarrow2x+4=-10.7=-70\)
\(\Rightarrow2x=-70+4=-66\)
\(\Rightarrow x=-66:2=-33\)
Vậy \(x=-33\)
\(2,\dfrac{2x+3}{5}=\dfrac{7x-3}{15}=\dfrac{7.\left(2x+3\right)}{7.5}=\dfrac{2.\left(7x-3\right)}{2.15}=\dfrac{14x+21}{35}=\dfrac{14x-6}{30}\)
Áp dụng tính chất của dãy tỉ số bằng nhau ta có :
\(\dfrac{2x+3}{5}=\dfrac{14x+21}{35}=\dfrac{14x-6}{30}=\dfrac{\left(14x+21\right)-\left(14x-6\right)}{35-30}=\dfrac{29}{5}\)
\(\Rightarrow\dfrac{2x+3}{5}=\dfrac{29}{5}\)
\(\Rightarrow2x+3=29\)
\(\Rightarrow2x=29-3=26\)
\(\Rightarrow x=26:2=13\)
\(3,\dfrac{11x-2}{7x+5}=\dfrac{11}{8}\)
\(\Rightarrow\dfrac{11x-2}{11}=\dfrac{7x+5}{8}=\dfrac{7.\left(11x-2\right)}{7.11}=\dfrac{11.\left(7x+5\right)}{8.11}=\dfrac{77x-14}{77}=\dfrac{77x+55}{88}=\dfrac{\left(77x+55\right)-\left(77x-14\right)}{88-77}=\dfrac{69}{11}\)
\(\Rightarrow\dfrac{11x-2}{11}=\dfrac{69}{11}\)
\(\Rightarrow11x-2=69\)
\(\Rightarrow11x=69+2=71\)
\(\Rightarrow x=\dfrac{71}{11}\)
Hãy nêu các căn bậc hai của các số sau:
a,8
b,2
c,3
d,7
e,144
g,156
h,139
i, 0,04
k, 1,75
l, 2,96
\(\sqrt{8}=2\sqrt{2}\)
\(\sqrt{2}=\sqrt{2}\)
\(\sqrt{3}=\sqrt{3}\)
\(\sqrt{7}=\sqrt{7}\)
\(\sqrt{144}=12\)
\(\sqrt{156}=2\sqrt{39}\)
\(\sqrt{139}=\sqrt{139}\)
\(\sqrt{0,04}=0,2\)
\(\sqrt{1,75}=\sqrt{1,75}\)
\(\sqrt{2,96}=\sqrt{2,96}\)
a) 2 căn 2
b) căn 2
c) căn 3
d) căn 7
e) 12
g) 2 căn 39
h) căn 139
i) 0,2
k) căn 7 / 2
l) căn 74 /5
a: \(2\sqrt{2};-2\sqrt{2}\)
b: \(\sqrt{2};-\sqrt{2}\)
c: \(\sqrt{3};-\sqrt{3}\)
d: \(-\sqrt{7};\sqrt{7}\)
e: 12;-12
g: \(2\sqrt{39};-2\sqrt{39}\)
h: \(\sqrt{139};-\sqrt{139}\)
i: 0,2;-0,2
k: \(\sqrt{1.75};-\sqrt{1.75}\)
l: \(\sqrt{2.96};-\sqrt{2.96}\)
1) Tính
a) \(\sqrt{225}\)
b) \(\sqrt{\left(\sqrt{3-1}\right)^2}\)
c) \(\sqrt{\left(1-\sqrt{7}\right)^2}\)
2) Tính
a) \(\sqrt{\left(a-1\right)^2}\) với a ≥ 1
b) \(\sqrt{\left(a+5\right)^2}\) với a ≤ -5
c) \(\sqrt{\left(9-a\right)^2}\)
Bài 2:
a: \(=\left|a-1\right|=a-1\)
b: \(=\left|a+5\right|=-a-5\)
c: \(=\left|a-9\right|\)
Tìm x bt
a) \(8\sqrt{x}+2x-9=5x+7+6\sqrt{x}-3x-12\)
b)\(2\sqrt{3x}+11x-18=5x 3+6\sqrt{3x}-21\)
a: \(\Leftrightarrow2\sqrt{x}=4\)
=>căn x=2
=>x=4
So sánh 2 số
\(\sqrt{8}\) và 8
vì : \(\sqrt{8}=2,828427125\)
mà : 8 > 2,828427125
nên => 8 > \(\sqrt{8}\)
8=\(\sqrt{64}\)
mà \(\sqrt{64}\)>\(\sqrt{8}\)
=> 8>\(\sqrt{8}\)
Chúc bạn học tốt nhé!!!
Tìm x ?
a) x2=5/7.x
b) 3x+3x+1=2430
c) (4x-1/3)3= -1/27
Giúp mình nha ! cần gấp !
a, x2 = \(\dfrac{5}{7}\) . x
x . x = \(\dfrac{5}{7}.x\)
=> x = \(\dfrac{5}{7}\)
b, 3x + 3x+1 = 2430
3x + 3x . 3 = 2430
3x . 3 = 2430 - 3x
3x = \(\dfrac{2430-3^x}{3^x}\)
3x = \(\dfrac{\left(2430:3^x\right)-1}{1}\)
a: =>x(x-5/7)=0
=>x=0 hoặc x=5/7
b: \(\Leftrightarrow3^x\cdot4=2430\)
=>3^x=2430/4(loại)
c: =>4x-1/3=-1/3
=>4x=0
=>x=0