Answer:
4 + √ 11 (7.31662479 … ) and 4 − √ 11 (0.68337520 …)
Step-by-step explanation:
d2 - 8d + 16 = 11
I'm going to assume that by d2 you mean d^2 and not d*2,
(d-4)(d-4) = (d-2)^2=11
d = 4 + √ 11 (7.31662479 … ) , 4 − √ 11 (0.68337520 …)
That's both surd and decimal form for each.
