Verified answer

| способ:

17² – 34 · 7 + 7² = 289 – 34 · 7 + 49 = 289 – 238 + 49 = 338 – 238 = 100 .

|| способ:

17²-34*7+7²=17²-2*17*7+7²=(17-7)²=10²=100.

P.S. 34=2*17;

По формуле: (a-b)²=a²-2ab+b².