Answer:
C
Step-by-step explanation:
x²-14x-49=0
x²-14x+49=49+49
(x-7)²=98
(x-7)²=49×2
x-7=±7√2
x=7+7√2=7(1+√2)≈7(1+1.414)≈7(2.414)≈16.898≈16.9
or
x=7-7√2=7(1-√2)≈7(1-1.414)≈-7×0.414≈-2.898≈2.9
B