144а² - 25в² = (12а)² - (5в)² = (12а-5в)(12а+5в)
2(x+3)(x+7) - 2x(x-2) = (x-2)(x+3)
2(x²+7x+3x+21) - (2x²-4x) = x²-2x+3x-6
2x²+14x+6x+42-2x²+4x-x²+2x-3x+6 = 0
-x²+23x+48 = 0
x²-23x-48 = 0
D = 529 - 4*(-48) = 721
√D = √721
x₁ = (23-√721)/2
x₂ = (23+√721)/2
2^50+2^51+2^52=2^50(1+2+2^2)=2^50*7; 3^17+3^18+3^19=3^17(1+3+3^2)=3^17*13.
(5^(1-5n))^2=5^2/5^10n
(4^(2n+1))^3=4^6n*4^3
(2.5)^11n=5^11n/2^11n
160=2^5*5
(5^2/5^10n*2^12n*2^6*5^11n/2^11n)/2^5*5=5^2*2^n*5^n*2^6/2^5*5=2^(n+1)5^(n+1)=
= 10^(n+1)