Answer:
-4 and 12
Step-by-step explanation:
(x-4)² is the same as (x-4)(x-4)
now we have
(x-4)(x-4) = 64
expand (x-4)(x-4)
x²-4x-4x+16 which is simplified to x²-8x+16
equate to 64
x²-8x+16 = 64
subtract 64 on both sides
x²-8x+16-64 = 0
x²-8x-48 = 0
to find x
what two numbers multiply to give -48 and add to give -8? That is -12 and 4 which we can write in brackets
(x-12)(x+4) = 0
equate each bracket to 0 to find x
x-12 = 0 and x+4 = 0
x = 12 and x = -4
