3(3x+2)=2(2x+3)
9x+6=4x+6
9x=4x
9x-4x=0
5x=0
x=0
А6=15 d=1
A6=a1+a5
A6=a1+d(n-1)
15=a1+5
A1=15-5
A1=10
a15=a1+d(n-1)
A15=10+1(15-1)
A15=24
Sn=(a1+an)/2 * n
S15=(10+24)/2 *15
S15=34/2 * 15
S15=17*15
S15=255
9 993 100 вот такой ответ
(-x + 5)(x + 5) = - (x - 5)(x + 5) = - (x² - 25 ) = 25 - x²
(- 10 + 6b)(- 10 - 6b) = -(6b - 10)(6b + 10) = - ( 36b² - 100) = 100 - 36b²
(8l + 5)(- 10 + 16l) = - 2(8l + 5)(5 - 8l) = - 2 (25 - 64l²) = 128l² - 50
(21s - 12)(8 + 14s) = 3 * 2 *(7s - 4)(4 + 7s) = 6(49s² - 16) = 294s² - 96
У=12/х
у=х-1
х-1=12/х
х-12/х=1
(х^2-12)/х=1
x^2-12=1*x
x^2-12=x
x^2-x-12=0
Дискриминант=1-4*1*(-12)=49
х1=1+7/2=4
х2=1-7/2=-3