(x+13) : 5 = 12
x+13 =12.5
x+13 =60
x =60-13
x =47
(x+13):5=12
(x+13)=5*12
(x+13)=60
x=60-13
x=47
Thực hiện các phép tính:
\(a.\dfrac{-5}{9}-\dfrac{-5}{12} \) \(b.\dfrac{-5}{12}:\dfrac{15}{4}\) c. \(\dfrac{1}{13}\) x \(\dfrac{8}{13}\) + \(\dfrac{5}{13}\) x \(\dfrac{1}{13}\) - \(\dfrac{14}{13}\)
Tính
12/1 x 5 + 12/5 x 9 + 12/9 x 13 + + 12/97 x 101
a = 9 phần 13 + 4 phần 13 x -5 + 12 - 4,13 x 17 phần 12
-5/7 x 3/13 - 5/7 x 10/13 + 12/7
Bài 1: Thực hiện các phép tính (Tính nhanh nếu có thể)
a) \(\dfrac{-5}{9}\) - \(\dfrac{-5}{12}\) b) \(\dfrac{-5}{12}\) : \(\dfrac{15}{4}\) c) \(\dfrac{1}{13}\) x \(\dfrac{8}{13}\) + \(\dfrac{5}{13}\) x \(\dfrac{1}{13}\) - \(\dfrac{14}{13}\)
Bài 2: Tìm \(x\), biết:
a) \(x=\dfrac{1}{5}+\dfrac{-3}{7}\) b) \(\dfrac{3}{5}-\dfrac{4}{7}\)\(:\)\(x=\dfrac{-9}{10}\) c) \(x-\left(\dfrac{-3}{4}\right)=\dfrac{-2}{3}-\dfrac{1}{2}\)
d) \(\dfrac{-5}{9}-x=\dfrac{1}{3}+\dfrac{7}{18}\)
Bài 3: Cho S = \(\dfrac{1}{2^2}+\dfrac{1}{3^2}+\dfrac{1}{4^2}+...+\dfrac{1}{10^2}\). Chứng minh rằng: \(S>\dfrac{9}{22}\)
tìm X , biết; a) |12-3x| =x +3 b) | 12-(x-13)| < 7 c) | 12 + (13 - 2x ) | < 5
7/13 x 7/15 - 5/12 x 7/13 + 7/13 x 8/15 = ?
-4/13 x 5/17 + -12/13 x 4/17 + 4/13
Tìm x biết:
a, x.12 +13= 1
b, 13.x-5= 21
12 tính nhanh
(-2)x(-3)x(-4)x(-5)x(-6)x(-7)
(-11)x(-12)x(-13)x(-14):((-13)x(+14))
(-1)x(5³ -(-4)³
