Раскроем скобки 2х^2+6-3x^5-9^2 =6-7x^2-3x^5
Производная: -14x-15x^4
A / B = 3
A = 3B
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1) A + 9B + 38 = 3B + 9B + 38 = 12B + 38 = 2 * ( 6B + 19 )
2) A + 3B + 19 = 3B + 3B + 19 = 6B + 19
3) [ 2 * ( 6B + 19 ) ] / ( 6B + 19 ) = 2
ОТВЕТ 2
680.
6х+56-72х=-2х-8
6х-72х+2х=-8-56
-64х=-64
х=-64÷(-64)
х=1
$$$$$$$
681.
3х-2-3х-15=-2+х-5
-17=-7+х
х=-17+7
х=-10
$$$$$$$$
682.
х-1+х+2=20+4х-5
2х+1=15+4х
2х-4х=15-1
-2х=14
х=-7
$$$$$$$$
683.
-2х+1-3х+12=12-4х+4
-5х+13=16-4х
-5х+4х=16-13
-х=3
х=-3