Question

Such an easy question, just need to know if I am right:

Identify which equation is a quadratic equation.

y = 3x + 4

y + x2 = (x − 2)(x + 7)

y = −4x(x − 4) + 2x

y + 3 = (x + 12)(x2 + 2)

I chose D.

Answer 1

Since it then becomes y = 2x^2 + 12x - 3

Answer 2

Let's go through the choices.
A has no squared term, so it can't be it.

Answer 3

That and it has to be x^2 format

Answer 4

With B, after you multiply the binomials on the right side, the x^2 term will cancel out with the x^2 term on the left, so there is no squared term anymore, so it's not it.

Answer 5

C is the example of quadratic equation.

Answer 6

Let's look at D. On the right side, when you multiply the binomials together, you have x and x^2. They multiply to x^3. That is not quadratic. It's cubic.

Answer 7

That and it would make 2x and 7x which is wrong

Answer 8

Ah I see

Answer 9

Now let's go back to C. -4x * x is quadratic, and there is no x^2 term anywhere that will cancel it out. So C is the answer

Answer 10

Ohhhhh ok I see, I skipped C because it was too long to think out :3

Answer 11

lol

Answer 12

But I see your reasoning thanks