Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
Bài 1 :
a) 16.(38−2)−38(16−1)
= 16 * 38 - 2* 16 - 16 *38 + 38
= - 32 +38
= 6
b) (−41).(59+2)+59(41−2)
= (-41) * 59 - 41 *2 + 41 * 59 - 59 *2
= 2(-41 - 59)
= 2* (-100)
= -200
Bài 2 :
Tìm các số x ; y ; x biết rằng :
x + y = 2 ; y + z = 3 ; z + x = -5
=> 2(x+ y + z)= 2+3+(-5)= 0
=> x+y +z =0
=> z= (x+y+z) -(x+y) = 0-2 =-2
x= (x+y+z) -(y+z) = 0-3 =-3
y = (x+y+z) - (x+z) = 0 -(-5) =0+5 =5
Vậy x= -2 ; y=-3 ; z=5
Bài 3 : Tìm x ; y ∈ Z biết rằng :
( y + 1 ) . xy - 1 ) = 3
(sao có 3 dấu ngoặc z?)
Bài 3 : Tìm x ; y ∈∈ Z biết rằng :
( y + 1 ) . ( xy - 1 ) = 3
\(6n+9⋮4n-1\)
\(\Rightarrow2.\left(6n+9\right)⋮4n-1\)
\(\Rightarrow12n+18⋮4n-1\)
\(\Rightarrow12n-3+21⋮4n-1\)
\(\Rightarrow3.\left(4n-1\right)+21⋮4n-1\)
Vì \(3.\left(4n-1\right)⋮4n-1\Rightarrow21⋮4n-1\)
Mà 4n - 1 chia 4 dư 3; \(4n-1\ge-1\) do \(n\in N\)
\(\Rightarrow4n-1\in\left\{-1;3;7\right\}\)
\(\Rightarrow4n\in\left\{0;4;8\right\}\)
\(\Rightarrow n\in\left\{0;1;2\right\}\)
15-2n:n+1
2(n+1):n+1
15-2n-2(n+1):n+1
15-2n-2n-2:n+1
15-2:n+1
13:n+1
→n+1={1;13}
→n={9;12}
a: \(=\dfrac{1}{3}-\dfrac{37}{100}+\dfrac{1}{8}-\dfrac{32}{25}+\dfrac{-5}{2}+\dfrac{3}{2}\)
\(=\dfrac{1}{3}+\dfrac{1}{8}-1-\dfrac{37}{100}-\dfrac{128}{100}\)
\(=\dfrac{8+3-24}{24}-\dfrac{165}{100}\)
\(=\dfrac{-263}{120}\)
b: \(=\dfrac{5}{22}+\dfrac{3}{13}-\dfrac{13}{8}-\dfrac{2}{11}+\dfrac{3}{2}\)
\(=\dfrac{5}{22}-\dfrac{4}{22}-\dfrac{13}{8}+\dfrac{12}{8}+\dfrac{3}{13}\)
\(=\dfrac{1}{22}-\dfrac{1}{8}+\dfrac{3}{13}=\dfrac{173}{1144}\)
a: \(=\dfrac{1}{3}-\dfrac{37}{100}+\dfrac{1}{8}-\dfrac{32}{25}-\dfrac{5}{2}+\dfrac{3}{2}\)
\(=\dfrac{11}{24}+\left(-\dfrac{37}{100}+\dfrac{1}{8}-1\right)\)
\(=\dfrac{11}{24}-\dfrac{249}{200}=-\dfrac{59}{75}\)
b: \(=\dfrac{5}{22}+\dfrac{3}{13}-\dfrac{13}{8}-\dfrac{2}{11}+\dfrac{3}{2}\)
\(=\dfrac{5}{22}-\dfrac{4}{22}+\dfrac{3}{13}-\dfrac{13}{8}+\dfrac{12}{8}\)
\(=\dfrac{1}{22}+\dfrac{3}{13}-\dfrac{1}{8}=\dfrac{173}{1144}\)
bó tay.........ko có quy luật nào như vậy cả