3) а) 8(а-b+с)=8a - 8b + 8c

б) -5(m-n-k)= - 5m + 5n + 5k

в) a(b-m+n) = ab-am+an

г) -4(6x-3c+4)= - 24x+12c-16

4) a) 6-(a+4)-(8a-5) = 6-a-4-8a+5 = - 9a+7

б) -(2x-8)-6x-4 = -2x+8-6x-4 = -8x+4

в) 3a+(-9a+4) = 3a-9a+4 = - 6a+4

г)-5y+(-y-1) = - 5y-y+1= - 6y+1

5) a) (x-8)(x+2) = 0

x^2+2x-8x-16 = 0

x^2-6x-16=0

D = b^2-4ac = (-6)^2-4*1*(-16) = 36+64=100

√D = √100 = 10

x1 = -b - √D / 2a = 6-10 / 2*1 = -4 / 2 = -2

x2 = -b + √D / 2a = 6+10 / 2*1 = 16 / 2 = 8

Ответ: -2; 8

б) (9+a)(3-a) = 0

27-9a+3a-a^2 = 0

-a^2-6a+27 = 0

D = 36+108 = 144

√D = 12

x1 = 6-12 / -2 = 3

x2 = 18/ -2 = -9

Ответ: -9; 3

в) 16-5y = 12y-1

16-5y-12y+1 = 0

-17y=-17

y = 1

Ответ 1

г) 2(y+3) = 21-3y

2y+6-21+3y = 0

5y=15

y = 3

Ответ 3

д) -(3y+7) = 8-2(8-y)

-3y-7-8+16-2y = 0

-5y = -1

y = 0,2

Ответ 0,2