contestada

When 3 times a number is added to the square of the number, the result is 40. Determine the number

Respuesta :

Answer:

5 or -8

Step-by-step explanation:

[tex](3 \times x) + x {}^{2} = 40[/tex]

[tex]3x + {x}^{2} = 40[/tex]

[tex] {x}^{2} + 3x - 40 = 0[/tex]

using factorization method

[tex]( {x}^{2} + 8x) ( - 5x - 40) = 0[/tex]

[tex]x(x + 8) - 5(x + 8) = 0[/tex]

[tex](x - 5)(x + 8) = 0[/tex]

[tex]x - 5 = 0[/tex]

or

[tex]x + 8 = 0[/tex]

[tex]x = 5[/tex]

or

[tex]x = - 8[/tex]