Answer:

Step-by-step explanation:
Quadratic function-
It is a function that can be represented by an equation of the form
, where
In a quadratic function, the greatest power of the variable is 2.
As in the first option the highest power is 3, so it is not a quadratic function.
Even though the power of x is 2 in the third option, but as it is in the denominator, so the overall power of x becomes -2. Hence it is not a quadratic function.
As the coefficient of
is 0 in case of fourth option, so it is not a quadratic function.
Equation in option 2 satisfies all the conditions of quadratic function, hence it is the quadratic function.
This question makes no sense
Answer:
x = 22.5
Step-by-step explanation:

3 is no cuz obtuse angle is >90 degrees, all the angles together must equal 180 degrees, and if you try it, you get no. 5 is 25% of 45, which is $11.25.
First subtract the 7 from both sides and that would equal 2x+9=2x then subtract 2x and the answer is 9