Question

Seguindo o exemplo, responda a questão a seguir:
Exemplo: 49 . 51= (50-1) . (50+1)=
=502 - 12=
= 2500 – 1
= 2499
1. Resolva com o passo a passo, igual ao exemplo:
a) 28 . 32
b)71 . 69
c)87 . 93
d)54 . 46
e)63 . 57
f)18 . 22

Answer 1

a) (30-2).(30+2)=30^2-2^2=900-4=896
b) (70+1)(70-1)=70^2-1^2=4900-1=4899
c) (90-3)(90+3)=90^2-3^2=8100-9=8091
d) (50+4)(50-4)=50^2-4^2=2500-16=3484
e) (60+3)(60-3)=60^2-3^2=3600-9=3591
f) (20-2)(20+2)=20^2-2^2=400-4=396