Quadratic graphs - Quiz 1.   Last unanswered question  Question  Next unanswered question

Question 1 lion

Which of the following graphs represent   y = x2- 2x?
a) PIC   b) PIC
c) PIC   d) PIC

 

Not correct. Choice (a) is false.
Try again, this is the line   y = x- 2.
Not correct. Choice (b) is false.
Try again, this is the graph of the equation       2
y = x - x- 2.
Your answer is correct.
     2
y = x -2x = x(x - 2)  so it is concave up and passes through (0,0)  and (2,0).
Not correct. Choice (d) is false.
Try again, this graph is concave down.
Question 2 lion

Which of the following graphs represent               2
y = 3 - 2x- x ?
a) PIC   b) PIC
c) PIC   d) PIC

 

Not correct. Choice (a) is false.
Try again, this is       2
y = x + 4x+ 3.
Your answer is correct.
            2
y = 3- 2x - x = (3 +x)(1- x)    so it is concave down and passes through (-3 ,0)  and (1,0).
Not correct. Choice (c) is false.
Try again, this is         2
y = - (x - 4x +3).
Not correct. Choice (d) is false.
Try again, this is       2
y = x - 4x+ 3.
Question 3 lion

Consider the graph of        2
y = ax    below.
Which of the following statements about the graph is true?

PIC
a) The graph has a minimum and the coefficient of x2 , a  is negative.
b) The graph has a maximum and the coefficient of x2, a  is negative.
c) The graph has a maximum and the coefficient of x2  is positive.
d) The graph has a minimum and the coefficient of x2, a  is positive.

 

Not correct. Choice (a) is false.
Try again, the graph does have a minimum but you have the coefficient wrong.
Not correct. Choice (b) is false.
Try again, the graph does not have a maximum.
Not correct. Choice (c) is false.
Try again, if the graph has a maximum then a  must be negative.
Your answer is correct.
The graph is concave up so it has a minimum and a  is positive.
Question 4 lion

Consider the graph of                   2
y = b0 +b1x + b2x  below.
Which of the following statements about the coefficients b0  and b2  is true?

PIC
a) b0 = -3 , b2 > 0.    b) b0 =- 2, b2 >0 .
c) b0 =- 2, b2 <0 .    d) b0 =- 1, b2 <0 .

 

Not correct. Choice (a) is false.
Try again, you have the minimum not the y  -intercept for b0.
Your answer is correct.
The y  -intercept is -2 so b0 = -2  and the parabola is concave up so b2 > 0.
Not correct. Choice (c) is false.
Try again, you have the wrong concavity.
Not correct. Choice (d) is false.
Try again, you have the wrong concavity and the wrong intercept.
Question 5 lion

Which of the following graphs represents   y = b0 + b1x+ b2x2  where b0 = - 1  and b2 < 0 ?
PIC       PIC
PIC       PIC
a) 1 and 4.   b) 1 and 2.
c) 2 and 3.   d) 3 and 4.

 

Your answer is correct.
Correct. All of the graphs have b0 = - 1  but only 1 and 4 are concave down, as required.
Not correct. Choice (b) is false.
Try again, 1 has b2 < 0  but 2 has b2 > 0 .
Not correct. Choice (c) is false.
Try again, 2 and 3 both have b2 > 0.
Not correct. Choice (d) is false.
Try again, 3 has b2 > 0 .