Odpowiedź:
a)
[tex]4x^2+20x+25=0\\Korzystamy - > (a+b)^2\\\\(2x+5)^2=0\\2x+5=0\\2x = -5\\x = -\frac{5}{2}[/tex]
b)
[tex]16x^2-25 = 0\\Korzystamy - > a^2-b^2=(a-b)(a+b)\\(4x)^2-5^2=0\\(4x-5)(4x+5)=0\\4x-5=0 \\4x = 5\\ x = \frac{5}{4}\\ lub \\4x+5=0\\4x = -5\\x = -\frac{5}{4}[/tex]