Which equation is a quadratic equation?

y = −4(3x + 2)

y + 3x3 = (x − 2)(3x + 8)

y − 3 = (2x2 + 11)(x − 1) + 3x

y + 5x = −2x(4 − x) + 1

Question

Which equation is a quadratic equation? 

 y = −4(3x + 2) 

 y + 3x3 = (x − 2)(3x + 8) 

 y − 3 = (2x2 + 11)(x − 1) + 3x 

 y + 5x = −2x(4 − x) + 1

jdoe0001 · Answer

http://www.mathsisfun.com/algebra/quadratic-equation.html

jdoe0001 · Answer

well, it isn't the 1st, the 1st only has 1 degree, that is the highest exponent for "x" is 1

the 2nd one, it has a $\bf 3x^3 $  so that's a 3rd degree one, so no dice there

the 3rd one, well, it has a $\bf (2x^2+11)(x-1) \implies 2x^3-2x^2+11x-11$
so that one has also a 3rd degree for "x", so no that one either

the 4th one, it has a $\bf -2x(4-x)+1 \implies -8x+2x^2+1$
so the highest exponent for "x" there is 2, thus :)