Respuesta :
Remark
You need to complete the square.
Solution
y = 2x^2 + 8x + 6 Put brackets around the first 2 terms.
y = (2x^2 + 8x) + 6 Take out the common factor of 2
y = 2(x^2 + 4x) + 6 Take 1/2 the coefficient of the linear term (4x) and square it.
y = 2(x^2 + 4x + (4/2)^2 ) + 6 The 6 is not affected yet.
y = 2(x^2 + 4x + 2^2) + 6
y = 2(x^2 + 4x + 4) + 6 Take twice the third term and subtract it from 6
y = 2(x^2 + 4x + 4) + 6 - 2*4
y = 2(x^2 + 4x + 4) + 6 - 8
y = 2(x^2 + 4x + 4) - 2 Express the 3 terms inside the brackets as a square.
y = 2(x + 2)^2 - 2
The vertex is at (-2,-2) and the axis of symmetry is x = - 2
I'll post this much and edit it to include a graph, which you should always make for a problem like this one.
You need to complete the square.
Solution
y = 2x^2 + 8x + 6 Put brackets around the first 2 terms.
y = (2x^2 + 8x) + 6 Take out the common factor of 2
y = 2(x^2 + 4x) + 6 Take 1/2 the coefficient of the linear term (4x) and square it.
y = 2(x^2 + 4x + (4/2)^2 ) + 6 The 6 is not affected yet.
y = 2(x^2 + 4x + 2^2) + 6
y = 2(x^2 + 4x + 4) + 6 Take twice the third term and subtract it from 6
y = 2(x^2 + 4x + 4) + 6 - 2*4
y = 2(x^2 + 4x + 4) + 6 - 8
y = 2(x^2 + 4x + 4) - 2 Express the 3 terms inside the brackets as a square.
y = 2(x + 2)^2 - 2
The vertex is at (-2,-2) and the axis of symmetry is x = - 2
I'll post this much and edit it to include a graph, which you should always make for a problem like this one.
