Question

what must be subtracted from x³+3x-9 to get 3x³+x²+3​

Answer 1

Answer:

$let \: the \: number \: to \: be \: subtracted \: be \: z.... \\ so \: {x}^{2} + 3x - 9 - z = 3 {x}^{3} + {x}^{2} + 3 \\ - z = 3 {x}^{3} + {x}^{2} + 3 - ( {x}^{2} + 3x - 9) \\ - z = 3 {x}^{3} + {x}^{2} + 3 - {x}^{2} - 3x + 9 \\ - z = 3 {x}^{3} + {x}^{2} - {x}^{2} - 3x + 9 + 3 \\ - z = 3 {x}^{3} - 3x + 12 \\ \\ multiplying \: both \: the \: sides \: by \: - 1 \\ \\ - 1 \times - z = - 1(3 {x}^{3} - 3x + 12) \\ z = - 3 {x}^{3} + 3x - 12.....$

Answer 2

Answer:

-2x³ - x² + 3x -12

Step-by-step explanation:

what must be subtracted from x³ + 3x -9 to get 3x³+ x² + 3