X- Скорость лодки.
4(x+1.5)=6(x-1.5)
4x+6=6x-9
4x-6x=-6-9
-2x=-15
x=-15/-2
x=7.5 км/ч
Ответ: Скорость лодки 7.5 км/ч
Объяснение:
-2+0.6b-2/5*(3b-5)
раскрываем скобки, выполнив умножение на 2
-2+0.6b-6/5b+2
сокращаем
3/5b-6/5b
считаем
-3/5b=0.6b=0.6*1/3
1/5
373
a - b 8b⁴ (a - b) * 4b³ * 2b 2b
--------- * -------------- = ------------------------- = ---------
4b³ a² - ab a* (a - b) * 4b³ a
---------------------------------------------------------------------------------------------------
x² - 4y² 28x² (x - 2y)*(x + 2y) * 4x * 7x
------------- * ---------------------- = ------------------------------------- =
35xy x² - 4xy + 4y² 5y * 7x * (x - 2y)²
4x* (x + 2y) 4x² + 8xy
= --------------------- = --------------------
5y * (x - 2y) 5xy - 10y²
--------------------------------------------------------------------------------------------------
ax + ay + 2y + 2x 6 (x * (a + 2) + y (a + 2)) * 6
-------------------------- * ------------------ = ---------------------------------------- =
2a + 4 5x + 5y 2*(a + 2) * 5 * (x + y)
(a + 2) * (x + y) * 6
= ------------------------------ = 6 / 10 = 0,6
10 * (a + 2)* (x + y)
-------------------------------------------------------------------------------------------------
5 (2 - a) * (2 - a) * 5 10 - 5a 5a - 10
(2 - a)² * ---------------- = -------------------------- = ---------------- = ---------------
ab - 2b -1 * b * (2 - a) -b b
------------------------------------------------------------------------------------------------
373)
m² - 4n² (m + 2n)² (m + 2n)*(m - 2n) 9m²
------------- : ---------------- = ------------------------- * ---------------------------- =
3mn 9m² 3mn (m + 2n)*(m + 2n)
(m + 2n)*(m - 2n) * 9m² (m - 2n) * 3m 3m² - 6mn
= ------------------------------------ = --------------------- = -----------------
(m + 2n)*(m + 2n) * 3mn (m + 2n) * n 2n² + mn
----------------------------------------------------------------------------------------
2x² - xy x + y (2x - y) * (x + y)
(2x - y) : ---------------- = (2x - y) * -------------- = ----------------------- =
x + y 2x² - xy x * (2x - y)
x + y
= ------------
x
--------------------------------------------------------------------------------------------------
a³ - 1 2a² + 2a + 2 (a - 1) * (a² + a + 1) 5a²
------------ : -------------------- = --------------------------- * ------------------------ =
2a³ 5a² 2a³ 2 * (a² + a + 1)
(a - 1) * (a² + a + 1) * 5 * a² 5 * (a - 1) 5a - 5
= ---------------------------------------- = ---------------- = ---------------
2 * (a² + a + 1) * 2a * a² 4a 4a
------------------------------------------------------------------------------------------------
a² - 9 a + 3 (a + 3) * (a - 3) 9 * (a + 2) * (a² - 2a + 4)
---------------- : ---------------- = ----------------------- * ------------------------------------- =
a² - 2a + 4 9a³ + 72 a² - 2a + 4 a + 3
(a + 3) * (a - 3) * 9 * (a + 2) * (a² - 2a + 4)
= ----------------------------------------------------------- = (a - 3) * 9 * (a + 2) =
(a + 3) * (a² - 2a + 4)
= 9 * (a² + 2a - 3a - 6) = 9 * (a² - a - 6) = 9a² - 9a - 54 /////////////////////////
