contestada

Solve by completing the square.
y² + 30y = -7
Write your answers as integers, proper or improper fractions in simplest form, or decimals
rounded to the nearest hundredth.
y =
Submit
or y =

Respuesta :

mhanifa

Answer:

  • y = 0.24 or y = - 29.76

==============================

Identity of the square of a sum of two numbers:

  • (a + b)² = a² + 2ab + b²

Given equation:

  • y² + 30y = - 7

We can see one of the numbers is y, and the second one is 15 as twice the product is 30y.

Add 15² = 225 to both sides to complete the square, then solve it:

  • y² + 2*15y + 15² = 225 - 7
  • (y + 15)² = 218
  • y + 15 = ± √218
  • y = - 15 ± √218
  • y = - 15 ± 14.76 (rounded to the nearest hundredths)
  • y = 0.24 or y = - 29.76

Otras preguntas