Question 1:
To start off this question, we can tell that this is a square because it has 4 right angles and 4 congruent sides.
A square has four parallel sides and 4 congruent sides, so a square is a rhombus and parallelogram.
A square has 4 right angles, so it's also a rectangle.
A square has 4 sides, so it's also a quadrilateral.
The first choice is your answer.
Question 2:
Not all quadrilaterals are rectangles, so A is incorrect.
Not all quadrilaterals are squares, so B is incorrect.
All rectangles are types of quadrilaterals, so C is correct.
Not all quadrilaterals are parallelograms, so D is incorrect.
Thus, C is your answer.
Question 3:
The first choice will not work because a rhombus will satisfy those conditions, and a rhombus is not always a square.
The second choice will work because only a square will satisfy that condition because only squares have 4 congruent sides along with equal diagonals.
Thus, the second choice is your answer.
Have an awesome day! :)
Answer:
D. 
or 
Step-by-step explanation:
The given equation is:
Divide through by 3;
Add the square of half the coefficient of x to both sides.
The left hand side is now a perfect square:
Take square root
D. or
