Verified answer

f(x) = kx - 2

f(1) = k - 2

f(f(1)) = f(k-2) = k*(k - 2) - 2 = -3

k² - 2k + 1 = 0

(k - 1)² = 0

k = 1

f(x) = x - 2

f(1) = 1 - 2 = -1

f(f(1)) = f(-1) = -1 -2 = -3

pronto

f(x) = kx - 2

f(1) = k - 2

f(f(1)) = k.f(1) - 2

f(f(1)) = k(k - 2) - 2

f(f(1)) = k² - 2k - 2

f(f(1)) = -3

k² - 2k - 2 = -3

k² - 2k + 1 = 0

(k - 1)² = 0

k - 1 = 0

k = 1

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