Cho biết
\(1^{2+2^2+3^2+.......+10^2=385}\)
Tính tổng:
a)\(^{2^2+4^2+6^2+........+20^2}\)
b)\(\left(0,25\right)^2+\left(0,5\right)^2+...........+\left(2,5\right)^2\)
Những câu hỏi liên quan
Cho \(1^2+2^2+3^2+...+10^2=385\). Tính
\(S=\left(0,25\right)^2+\left(0,5\right)^2+\left(0,75\right)^2+...+\left(2,5\right)^2\)
Ta có :
\(S=\left(0,25\right)^2+\left(0,5\right)^2+...+\left(2,5\right)^2\)
\(\Rightarrow4S=2^2.\left(0,25\right)^2+2^2.\left(0,5\right)^2+.....+2^2.\left(2,5\right)^2\)
\(\Rightarrow4S=1^2+2^2+....+10^2\)
\(\Rightarrow4S=385\)
\(\Rightarrow S=\frac{385}{4}\)
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C 25.left(-frac{1}{3}right)^3+frac{1}{5}-2.left(-frac{1}{2}right)^2-frac{1}{2}D left(-2right)^3.left(frac{3}{4}-0,25right):left(2frac{1}{4}-1frac{1}{6}right)E 5sqrt{16}-4sqrt{9}+sqrt{25}-0,3sqrt{400}F left(-frac{3}{2}right)+|-frac{5}{6}|-1frac{1}{2}:6G frac{0,5+0,left(3right)-0,1left(6right)}{2,5+1,left(6right)-0,8left(3right)}
Đọc tiếp
C = \(25.\left(-\frac{1}{3}\right)^3+\frac{1}{5}-2.\left(-\frac{1}{2}\right)^2-\frac{1}{2}\)
D = \(\left(-2\right)^3.\left(\frac{3}{4}-0,25\right):\left(2\frac{1}{4}-1\frac{1}{6}\right)\)
E = \(5\sqrt{16}-4\sqrt{9}+\sqrt{25}-0,3\sqrt{400}\)
F =\(\left(-\frac{3}{2}\right)+|-\frac{5}{6}|-1\frac{1}{2}:6\)
G = \(\frac{0,5+0,\left(3\right)-0,1\left(6\right)}{2,5+1,\left(6\right)-0,8\left(3\right)}\)
C = \(25.\left(\frac{-1}{3}\right)^3\) \(+\frac{1}{5}\) \(-2.\left(\frac{-1}{2}\right)^2\) \(-\frac{1}{2}\)
C = \(25.\left(\frac{-1}{27}\right)+\frac{1}{5}\) \(-2.\frac{1}{4}\) \(-\frac{1}{2}\)
C = \(\frac{-25}{27}\) \(+\frac{1}{5}\) \(-\frac{1}{2}\) \(-\frac{1}{2}\)
C = \(\frac{-25}{27}\) \(+\frac{1}{5}\) \(-1\)
C = \(\frac{-125}{135}\) \(+\frac{27}{135}\) \(-\frac{135}{135}\)
C = \(\frac{-233}{135}\)
D = \(-8.\left(\frac{3}{4}-\frac{1}{4}\right):\left(\frac{9}{4}-\frac{7}{6}\right)\)
D = \(-8.\frac{1}{2}\) \(.\frac{12}{13}\)
D = \(-4.\frac{12}{13}\)
D = \(\frac{-48}{13}\)
E = \(5\sqrt{16}\) \(-4\sqrt{9}\) \(+\sqrt{25}\) \(-0,3\sqrt{400}\)
E = \(5.4-4.3+5-0,3.20\)
E = \(20-12+5-6\)
E = \(8+\left(-1\right)\)
E = \(7\)
F = \(\left(\frac{-3}{2}\right)\) \(+\left|\frac{-5}{6}\right|\) \(-1\frac{1}{2}\) \(:6\)
F = \(\left(\frac{-3}{2}\right)\) \(+\frac{5}{6}\) \(-\frac{3}{2}\) \(.\frac{1}{6}\)
F = \(\left(\frac{-3}{2}\right)\) \(+\frac{5}{6}\) \(-\frac{1}{4}\)
F = \(\left(\frac{-18}{12}\right)\) \(+\frac{10}{12}\) \(-\frac{3}{12}\)
F = \(\frac{-11}{12}\)
Chúc cậu hk tốt ~
Thực hiện phép tính:
A=\(\left(3\frac{1}{3}+2,5\right):\left(3\frac{1}{6}-4\frac{1}{5}\right)-\frac{11}{31}\)
B=\(\left(-6\right).10:\left[-0,25+\frac{1}{2}:\left(-2\right)\right]+1\frac{3}{4}\)
A \(=\frac{35}{6}.\left(\frac{-30}{31}\right)-\frac{11}{31}=\frac{-175}{31}-\frac{11}{31}=\frac{-186}{31}=-6\)
\(B=-60:\left(\frac{-1}{2}\right)+\frac{7}{4}=30+\frac{7}{4}=\frac{127}{4}\)
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A=\(\left(3\frac{1}{3}+2,5\right):\left(3\frac{1}{6}-4\frac{1}{5}\right)-\frac{11}{31}\)
B=\(\left(-6\right).10:\left[-0,25+\frac{1}{2}:\left(-2\right)\right]+1\frac{3}{4}\)
\(A=\left(3\dfrac{1}{3}+2,5\right):\left(3\dfrac{1}{6}-4\dfrac{1}{5}\right)-\dfrac{11}{31}\\ =\left(\dfrac{10}{3}+\dfrac{5}{2}\right):\left(\dfrac{19}{6}-\dfrac{21}{5}\right)-\dfrac{31}{11}\\ =\left(\dfrac{30}{6}+\dfrac{15}{6}\right):\left(\dfrac{95}{30}-\dfrac{126}{30}\right)-\dfrac{31}{11}\\ =\dfrac{45}{6}:\dfrac{-21}{30}-\dfrac{31}{11}\\ =\dfrac{15}{2}\times\dfrac{-10}{7}-\dfrac{31}{11}=-\dfrac{75}{7}-\dfrac{31}{11}=-\dfrac{825}{77}-\dfrac{217}{77}=\dfrac{-1042}{77}\)
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\(B=\left(-6\right).10:\left[-0,25+\dfrac{1}{2}:\left(-2\right)\right]+1\dfrac{3}{4}\\ =-60:\left(\dfrac{-1}{4}+\dfrac{1}{2}.\dfrac{-1}{2}\right)+1\dfrac{3}{4}\\ =-60:\left(\dfrac{-1}{4}+\dfrac{-1}{4}\right)+1\dfrac{3}{4}\\ =-60:\left(\dfrac{-1}{2}\right)+1\dfrac{3}{4}=120+1\dfrac{3}{4}=121\dfrac{3}{4}\)
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Giup mình bài này với !
Cho biết \(1^2+2^2+3^2+4^2+5^2+6^2+7^2+8^2+9^2+10^2=385\) . Tính
A = \(2^2+4^2+6^2+8^2+...+18^2+20^2\)
B = \(\left(12^2+14^2+16^2+18^2+20^2\right)-\left(1^2+3^2+5^2+7^2+10^2\right)\)
Ta thấy A gấp 12+22+....+102 4 lần nên Tổng A gấp 4 lần nó
=> A=385.4=1540
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Bài 1.Tính hợp lý
a) \(\text{(0,5)}^3\) .\(2^3\)
b) \(\text{(0,25)}^2\).16
c) \(\left(\dfrac{3}{5}\right)^3:\left(\dfrac{-27}{1000}\right)\)
d) \(\dfrac{4^2.25^2+32.125}{2^3.5^2}\)
e) \(\dfrac{4^5.21+4^5.19}{2^{10}.11+2^{10}.5}\)
a: \(\left(0.5\right)^3\cdot2^3=1\)
b: \(\left(0.25\right)^2\cdot16=1\)
c: \(\left(\dfrac{3}{5}\right)^3:\left(-\dfrac{27}{1000}\right)=\dfrac{3^3}{5^3}\cdot\dfrac{-1000}{27}=\dfrac{-1000}{125}=-8\)
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a)\(4x-3=4-3x\)
b)\(3+\left(x-5\right)=2\left(3x-2\right)\)
c)\(2\left(x-\frac{1}{4}\right)-4=-6\left(-\frac{1}{3}+0,5\right)+2\)
d)\(2.\left(x-0,5\right)+3=0,25.\left(4x-1\right)\)
a) 4x - 3 = 4- 3x
<=> 4x + 3x = 4 + 3
<=> 7x = 7
<=> x = 1
b) 3 + (x - 5) = 2 ( 3x - 2)
<=> 3 + x - 5 = 6x - 4
,<=> x- 2 = 6x - 4
<=> 4 - 2 = 6x - x
<=> 2 = 5x
,<=> 5x = 2
<=> x = \(\frac{2}{5}\)
c) 2( x - \(\frac{1}{4}\)) - 4 = -6 ( -\(\frac{1}{3}\)+ 0,5) + 2
<=> 2x -\(\frac{1}{2}\)- 4 = 2 - 3 + 2
<=> 2x- \(\frac{9}{2}\)= 1
,<=> 2x = 1 + \(\frac{9}{2}\)= \(\frac{11}{2}\)
<=> x = \(\frac{11}{4}\)
d) 2 ( x - 0,5) + 3 = 0,25 ( 4x - 1)
<=> 2x - 1 + 3 = x - 0,25
<=> 2x + 2 = x - 0,25
<=> 2x - x = -2 - 0,25
<=> x = -2
Cho biết : \(1^2+2^2+3^2+...+10^2=385.\)Tính nhanh : \(\left(12^2+14^2+16^2+18^2+20^2\right)-\left(1^2+3^2+5^2+7^2+9^2\right)\)
Tính:
\(a.\frac{8^5.\left(-5\right)^8+\left(-2\right)^5.10^9}{2^{16}.5^7+20^8}\)
\(b.\frac{\left(-0,25\right)^{-5}.9^4.\left(-2\right)^{-3}-2^{-2}.6^9}{2^9.3^6+6^6.40}\)
\(c.\frac{2^{12}.3^5-4^6.9^2}{\left(2^2.3\right)^6+8^4.3^5}-\frac{5^{10}.7^3-25^5.49^2}{\left(125.7\right)^3+5^9.14^3}\)