Question

IV. Halla el valor numérico de las siguientes expresiones.

• X3 + 3X2 – 4X – 1 para X=3
• 3X2Y + 2XY2 para X=-2; Y=3
• M2 + 2mn + n2 para m=4; n=2

Answer 1

${x}^{3} + 3 {x}^{2} - 4x - 1 = \\ {3}^{3} + 3 \times {3}^{2} - 4 \times 3 - 1 = \\ 27 + 3 \times 9 - 4 \times 3 - 1 = \\2 7 + 27 - 12 - 1 = \\ 54 - 12 - 1 = \\ 42 - 1 = \\ 41$

$3 {x}^{2} y + 2x {y}^{2} = \\ 3 \times {( - 2)}^{2} \times 3 + 2 \times ( - 2) \times {3}^{2} = \\ 3 \times 4 \times 3 + 2 \times ( - 2) \times 9 = \\ 12 \times 3 + ( - 4) \times 9 = \\ 36 + ( - 36) = \\ 0$

${m}^{2} +2 mn + {n}^{2} = \\ {4}^{2} + 2 \times 4 \times 2 + {2}^{2} = \\ 16 + 2 \times 4 \times 2 + 4 = \\ 16 + 8 \times 2 + 4 = \\ 16 + 16 + 4 = \\ 32 + 4 = \\ 36$