Question

Помогите пожалуйста!!!

Answer 1

1. а) 3x(x^2-2x+3) = 3х^3-6x^2+9x

б) -4a(a^2-5ab+3b) = -4a^3+20a^2b-12ab

2. a) 7a(a-3b)-15b(3a+b)+4a(-a+8b) = 7a^2-21ab-45ab-15b^2-4a^2+32ab = 3a^2-34ab-15b^2

б) 3n^3(n-4)-2n(n^3-6n^2+2n)-n(9+n^3) = 3n^4-12n^3-2n^4+12n^3-4n^2-9n-n^4= -4n^2-9n

3. 4x(2x-4)-6x(3x-2) = 8x^2-16x-18x^2+12x = -10x^2-4x

если x=-7, то -10*(-7)^2-4*(-7) = -490-28 = -518

4. а) 3x(x-7)-x(4+3x)=5

3x^2-21x-4x-3x^2=5

-25x=5

x=-0,2

б) a(4a+1)-7(a^2-2a) = 3a(8-a)+6

4a^2+a-7a^2+14a = 24a-3a^2+6

15a = 24a+6

-9a = 6

a = -2/3

в) x+8/3 - x-2/5 = 2  I  *15

5(x+8)-3(x-2) = 30

5x+40-3x+6 = 30

2x+46 = 30

2x = -16

x = -8