16.
a) (a-5)(a+7)=a²+7a-5a-35= a²+2a-35
b) (z-8)(z-9) = z²-9z-8z+72 = z²-17z+72
c) (a-9)(a+9)= a²+9a-9a-81=a²-81
d) (p-3q)(p+3q)= p²+3pq-3pq-9q² = p²-9q²
e) (3a+b) (a-3b) = 3a²-9ab+ab-3b²=3a²-8ab-3b²
f) (7s+3t)(s-t) = 7s²-7st+3st-3t²=7s²-4st-3t²
17.
a) (a-0,3)(z+1)=az+a-0,3z-0,3
b) (a+1,7)(2-a) = 2a-a²+3,4-1,7a=0,3a-a²+3,4
c) (3+u)(0,2-u)= 0,6-3u+0,2u-u²=0,6-2,8u-u²
d) (v-8)(v+0,7)= v²+0,7v-8v-5,6=v²-7,3v-5,6
e) (3m-1,8)(m+9)=3m²+27m-1,8m-16,2=3m²+25,2m-16,2
f) (n-4)(3,7-4n)= 3,7n-4n²-14,8+16n=19,7n-4n²-14,8
18.
a) (3x+5)(x+2) = 3x²+6x+5x+10=3x²+11x+10
b) (6a-2)(5+3a) = 30a+18a²-10-6a=24a+18a²-10
c) (y+4)(2y-7) = 2y²-7y+8y-28=2y²+y-28
d) (9q-5)(q-13)=9q²-117q-5q+65=9q²-122q+65
e) (4r-f)(f-12r) = 4fr-48r²-f²+12fr=16fr-48r²-f²
f) (m+4n)(2m-5n) = 2m²-5mn+8mn-20n²=2m²+3mn-20n²
g) (7t+17)(14+2t)=98t+14t²+238+34t=132t+14t²+238
h)(12u+v)(13v+u)=156uv+12u²+13v²+uv=157uv+12u²+13v²
