Zad. 10
a) 5x(x-1)+(1-2x)(x+y)+(2x-1)*y, x=-1, y=0
[tex]5x^2-5x+x+y-2x^2-2xy=3x^2-4x+y-2xy\\3*(-1)^2-4*(-1)+0-2*(-1)*0=3+4+0+0=7[/tex]
b)(a-2b)(b+1)-3a(a+b-2)-(7a-2b^2), a=-2, b=-1
[tex]ab+a-2b^2-2b-3a^2-3ab+6a-7a+2b^2=-3a^2-2ab-2b\\-3*(-2)^2-2*(-2)*(-1)-2*(-1)=-3*4-4+2=-12-2=-14[/tex]
c) (2x-y)(3x+1)+(x-1)(x+1)+3xy, x=-2, y=1/2
[tex]6x^2+2x-3xy-y+x^2+x-x-1+3xy=7x^2+2x-y-1\\7*(-2)^2+2*(-2)-\frac{1}{2}-1=7*4-4- \frac{1}{2}-1=22\frac{1}{2}[/tex]
d) (a-b)(a+b)-2(a+b)(a+b), a=1/2, b=-1
[tex]a^2+ab-ab-b^2-2a^2-2ab-2ab-2b^2=-a^2-3b^2-4ab\\-(\frac{1}{2})^2-3*(-1)^2-4*\frac{1}{2}*(-1)=-\frac{1}{4}-3+2=-1\frac{1}{4}[/tex]
Zad. 11
a) 20x-40 = 20(x-2)
b) 16a-8 = 8(2a-1)
c)24x-36 = 12(2x-3)
d) -9y+18=-9(y-2)
e) -14z^2-21=-7(2z^2+3)
f) 120y^2-30y = 30y(4y-1)
g)40a^2b-16b=8b(5a^2-2)
h)18xz^3+36yz^2=18z^2(xz+2y)
i) 50ab^2-ab = ab(50b-1)
j) 42pq^2+35p^2q=7pq(6q+5p)
k) 8a^2b^3-24a^3b^3=8a^2b^3(1-3a)
l) 15xyz^3+45x^2yz^2=15xyz^2(z+3x)
