Question

(A) 4.
(B) 6.
(C) 12.
(D) 16.
(E) 20.

Answer 1

Resposta:

Alternativa C

Explicação passo-a-passo:

${ab}^{2} = bd.dc \\ {12}^{2} = x.(24 - x) \\ 24x - {x}^{2} = 144 \\ - {x}^{2} + 24x - 144 = 0 \\ \\ delta = {b}^{2} - 4ac \\ delta = {24}^{2} - 4.( - 1).( - 144) \\ delta = 576 - 576 = 0 \\ \\ x = \frac{ - b + delta}{2a} = \frac{ - 24}{2.( - 1)} = 12$