doar cele notate 5p si coroana si ma abonez si inima

24)N1=1987+2×(1986×1987):2

= 1987+1986×1987

=1987(1986+1)

=1987×1987

=1987^2

N2=64+2×64+3×64+....+49×64

=64×(1+2+3+...+49)

=64×(49×50):2

=64×(49×25)

=64×1225

=78400

25)4^n+4^n+1=10×2^1957

4^n + 4^n × 4^1=10×2^1957

2×4^n × 4 =10×2^1957

2× 2^2n+ 2^2

2×2^n ×2^2 +2^2

(2+2^2+2^2)× 2^n

10×2^n=10×2^1957

n=1957

28)A=3^2n+1 × 5^3n+2 - 9^n+1 ×5^3n+1

=3^2n+1×5^3n+2 - 3^2n+1 ×5^3n+1

Simplificam

=5^3n+2 - 5^3n+1

=5^3n × 5^2 -5^3n ×5^1

Simplificam

=5^2 -5^1

=25-5=20