Question

Which equation is a quadratic equation?

3x − y = 8x + 2

y = 7x(5 − 2x) + 9

7x2 + y = (3 + x)(7x − 1)

y − 3 = (x2 − 3)(8x + 3)

Answer 1

A quadratic equation in \(x\) is an equation in terms of \(x^2, x^1, x^0\). If you expand those equations above, which of them can be written in the form \(y=ax^2+bx+c\) where \(a,b,c\) are constants?

Answer 2

y = 7x(5 − 2x) + 9 this one

Answer 3

That's correct!

Answer 4

The first one doesn't have an \(x^2\) term, the third one the \(x^2\) terms cancel out, and the final one has an \(x^3\) term