* * * * * * * * * * * * * * * * * * * * * * * * *
08.
(2x -3)(3x+2) - x(5 x -7)= 6x²+4x - 9x -6 -5x² +7x = x²+2x - 6 . → 4
- - - - - - -
09. ( ( x-2)/(x-3) ) *( x + x/(2- x) ) = ( ( x-2)/(x-3) ) *x( 1 - 1 /(x- 2) ) =
( x( x-2)/(x-3) ) *( (x -2 -1)/(x -2) ) =( x( x-2)/(x-3) ) *(( x -3) /(x -2) ) = x . → 1
- - - - - - -
10. ( (-1/3)a³b)²*(3ab²)³ = (1/9)a⁶b² *27a³b⁶ =3a⁹b⁸ . → 4
- - - - - - -
11. (0,5x²y³)³/ (x³y⁵) : M = (3xy³)²/ (xy) ⇔(1/2)³x⁶y⁹/ (x³y⁵) : M = 3²x²y⁶/ (xy) ⇔
=(1/8)x³y⁴ : M = 9xy⁵ ⇒ M =(1/8)x³y⁴ / 9xy⁵ = x² / 72y → 2
- - - - - - -
12. 2x³ +3x² -8x -12 = x²(2x+3) -4(2x+3) =(2x+3)(x² - 4) =
(2x+3)(x- 2)(x+2) ≡ (x- 2)(x+2)(2x+3) → 2
ИЛИ
2x³+3x²- 8x -12 =2x³ - 8x +3x² -12 =2x(x² -4)+3(x² -4) =(x² -4)(2x +3) =
(x -2)(x+2)(2x +3)
- - - - - - -
13. x³ +x² - 4x - 4 =x²(x +1) - 4(x +1) =(x +1)(x² - 4) =(x +1)(x² - 2²) =
(x + 1)(x - 2)(x + 2) → 5
при d=10
Объяснение:
если правильно поняла условие ,то тогда так
7d-31= - (41-8d )
7 d- 31= -41+8d
7d -8d = -41 +31
-d = -10
d=10
проверка
7*10- 31= - (41- 8*10)
70- 31 = - (41- 80)
39= - (- 39)
39=39