346-50:5
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Bài 2:
a: \(A=2+2^2+2^3+...+2^{50}\)
\(\Leftrightarrow2A=2^2+2^3+2^4+...+2^{51}\)
=>\(A=2^{51}-2\)
b: \(B=3+3^2+3^3+...+3^{50}\)
\(\Leftrightarrow3B=3^2+3^3+...+3^{51}\)
\(\Leftrightarrow2B=3^{51}-3\)
hay \(B=\dfrac{3^{51}-3}{2}\)
c: \(C=2^2+2^4+...+2^{50}\)
\(\Leftrightarrow4C=2^4+2^6+...+2^{52}\)
\(\Leftrightarrow3C=2^{52}-4\)
hay \(C=\dfrac{2^{52}-4}{3}\)
1/ \(346-\left[124+30:\left(5^8:5^7\right).2^2.1018^0\right]\)
\(=346-\left[124+30:5.4.1\right]\)
\(=346-\left[124+6.4.1\right]\)
\(=346-\left[124+24\right]\)
\(=346-148\)
\(=198\)
2/ \(x^{17}=x\)
\(\Leftrightarrow x\in\left\{0;1\right\}\)
3/
a/ \(A=2+2^2+..........+2^{50}\)
\(\Leftrightarrow2A=2^2+2^3+..........+2^{51}\)
\(\Leftrightarrow2A-A=\left(2^2+2^3+.......+2^{51}\right)-\left(2+2^2+......+2^{51}\right)\)
\(\Leftrightarrow A=2^{51}-2\)
b,c tương tự
Tính
b, ( 27 + 65 ) + ( 346 - 27 - 65 )
= 27 + 65 + 346 - 27 - 65
= 27 + 65 + 346 + ( - 27 ) + ( -65 )
= 346 + [ 27 + ( -27 ) ] + [ 65 + ( -65 ) ]
= 346 + 0 + 0
= 346
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346 - X x 5 = 211
X x 5 = 346 - 211
X x 5 = 135
X = 135 : 5
X = 27
g) (15 + 37) + (52 – 37 – 17) = 15 + 37 + 52 – 37 – 17 = 15 + 52 – 17 = 50 h) (38 – 42 +14) - (38 – 42 - 15) = 38 – 42 +14 - 38 + 42 + 15 = 14 + 15 = 29 i) (27 + 65 ) + (346 - 27- 65) = 27 + 65 + 346 - 27- 65 = 346 k) - (27 + 65) - (346 – 27 - 65) = -27 - 65 - 346 + 27 + 65 = -346 l) (42 – 69 + 17) - (42 + 17) = 42 – 69 + 17 - 42 - 17 = – 69 m) 24. (16 - 5) – 16. (24 – 5 ) = 24. 16 - 24 . 5 - 16 . 24 + 16. 5 = - 24 . 5 + 16. 5 = -8 . 5 = -40 n) (-12). 47 – 12 . 52 + (-12) = -12 (47 - 52 + 1) = -12 . (-4) = 48 p) 51 . (69 - 25) – 69. (51 - 25) = 51 . 69 - 51 . 25 – 69. 51 + 69. 25 = - 51 . 25 + 69. 25 = (- 51+ 69).25 = 450 |
a:\(\Leftrightarrow7\left(2x-1\right)=346\cdot124-346=42558\)
=>2x-1=42558/7
=>2x=42565/7
hay x=42565/14
b: \(\Leftrightarrow2\left(7x+5\right)=23-\dfrac{4}{3}=\dfrac{65}{3}\)
=>7x+5=65/6
=>7x=35/6
hay x=5/6
a) 7(2x-1)=(346.124)-346
14x-7=42558
14x=42551
x=42551/14
b) 4/3+2(5+7x)=23
2(5+7x)=65/3
5+7x=65/6
7x=35/6
x=5/6
a) 346.124-7.(2x-1)=343
346.124-14x+7=343
42904-14x+7=343
-14x=343-42904-7
-14x=-42568
x=\(\dfrac{-42568}{-14}\)=\(\dfrac{42568}{14}\)=3,04
vậy x = 3,04
b)\(\dfrac{4}{3}\)+2(5+7x)=115:5
\(\dfrac{4}{3}\)+10+14x=23
14x=23-10-\(\dfrac{4}{3}\)
14x= \(\dfrac{35}{3}\)
x=\(\dfrac{35}{3}\):14
x=\(\dfrac{35}{42}\)=\(\dfrac{5}{6}\)
472 + 219 = 691
865 - 398 = 467
346 x 3 = 1038
675 : 5 = 135
472 + 219 = 691
865 - 398 = 467
346 x 3 = 1038
675: 5 = 135
Xong rồi nha !!
346 - 50 : 5
= 346 - 10
= 336
657-237