Answer :

[tex]y=4x^2-64=4(x^2-16)=4(x^2-4^2)=4(x-4)(x+4)\\\\-------------------------------\\\\4(x-4)(x+4)=0\iff x-4=0\ or\ x+4=0\\\\x=4\ or\ x=-4[/tex]

Answer:

x = 4

x = - 4

Step-by-step explanation:

y = 4x² - 64

y = 4(x² - 4²)

4(x - 4)(x + 4)

Two separate equations

x - 4 = 0

x + 4 = 0

x - 4 = 0

x - 4 + 4 = 0 + 4

x = 4

x + 4 = 0

x + 4 - 4 = 0 - 4

x = - 4