Answer:
3x^2 + 3xz
Step-by-step explanation:
Under the assumption that I need to distribute,
(x + z)(x + 2x)
(x + 2x) is (3x)
3x(x + z) becomes 3x*x and 3x*z
3x*x = 3x^2
3x*z = 3xz
combine, 3x^2 + 3xz
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