Explain why each expression is or is not a perfect square trinomial. (1) x^{2} + 6x + 12 x2+6x+12
(2) x^{2} + 18x + 81 x2+18x+81
(3) x^{2} + 15x + 25

Step-by-step explanation:

(1) x^2 + 6x + 12

- this has no real roots so NOT a perfect square trinomial.

(2) x^2 + 18x + 81

= (x + 9)(x + 9)

- 2 identical factors so it is a PST.

(3) x^2 + 15x + 25

does not factor as  2 does, so NO.

step-by-step explanation:

∆abc has the points a(1, 7), b(-2, 2), and c(4, 2) as its vertices. formed with the point d(1, 2) as its third vertex, then ∆abd is triangle.

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step-by-step explanation: