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Remember to include the positive and negative roots
(7x-2)^2=256
sqrt both sides
7x-2=+/-16
add 2 to both sides
7x=2+/-16
divdide both sides by 7
x=(2+/-16)/7)
x=(2+16)/7=18/7=2 and 4/7
x=(2-16)/7=-14/7=-2
x=2 and 4/7 or -2
The proof is to show your work