Question

a) (x + 1)(x + 4)

b) 2(2x + 3)(2x – 1)

c) –(x + 7)(x – 3)

d) 1 – (z + 5)(z – 1)

e) 2k [kwadrat] – (k + 3)(2k + 4)

f) -3(a + 2b)(a – b) [kwadrat]

Answer 1

a) (x + 1)(x + 4)=

=x²+4x+x+4

 

b) 2(2x + 3)(2x – 1)=

=2(4x²-2x+6x-3)=

=8x²-4x+12x-6=

=8x²+8x-6

 

c) –(x + 7)(x – 3)=

=-(x²-3x+7x-21)=

=-(x²+4x-21)=

=-x²-4x+21

 

d) 1 – (z + 5)(z – 1)=

=1-(z²-z+5z-5)=

=1-z²+z-5z+5=

=-z²-4z+6

 

e) 2k² – (k + 3)(2k + 4)=

=2k²-(2k²+4k+6k+12)=

=2k²-(2k²+10k+12)=

=2k²-2k²-10k-12=

=-10k-12

 

f) -3(a + 2b)(a – b)²=

=-3(a+2b)(a²-2ab+b²)=

=-3(a³-2a²b+ab²+2a²b-4ab²+2b³)=

=-3(a³-3ab²+2b³)=

=-3a²+9ab²-6b³