Answer:
1st option
Explanation:
x² - 19x + n
using the method of completing the square
add ( half the coefficient of the x- term )² to x² - 19x
x² + 2(- )x + (- )²
with n = (- )² = , then
(x - )² ← a perfect square trinomial
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)x + (- )² )² = 
, then )² ← a perfect square trinomial