Identify which equation is a quadratic equation?
I think its the first one but can anyone confirm it for me?

y = −6x − 3

y + x^2 = (x − 1)(x + 7)

y − 9 = (x − 1)(x^2 + 4)

y = 5x(x + 3) − 8

Question

Identify which equation is a quadratic equation?
I think its the first one but can anyone confirm it for me?

y = −6x − 3

y + x^2 = (x − 1)(x + 7)

y − 9 = (x − 1)(x^2 + 4)

y = 5x(x + 3) − 8

saifoo.khan · Answer

the standard form is 

ax^2 +bx +c = 0

so the answer is D.
bcoz:

y = 5x^2 + 15x -8

anonymous · Answer

oh okay thanks! :)

dumbcow · Answer

easy 
quadratic = 2nd power
If the highest exponent is 2 then its quadratic :)

dumbcow · Answer

linear = 1 as highest exponent
cubic = 3 as highest exponent

anonymous · Answer

y = 5x(x + 3) − 8