# How do you write the vertex form equation of the parabola #y=x^2+4x-5#?

##### 1 Answer

Feb 23, 2016

#### Explanation:

The standard form of a quadratic function is

# y = ax^2 + bx + c# The function

# y = x^2 + 4x - 5" is in this form "# and by comparison a = 1 , b = 4 and c = -5

The vertex form of the equation is

# y = a(x - h )^2 + k# where (h , k ) are the coords of the vertex.

x-coord of vertex (h)

# = (-b)/(2a) = (-4)/2 = -2# and y-coord (k) =

#(-2)^2 + 4 (-2) - 5 = 4-8-5 = -9# hence (h , k ) = (-2 , -9) and a = 1

#rArr y = (x + 2 )^2 - 9 " is vertex form of equation "#