Question

Answer the questions about the following function.

f(x) = 3x²-x-2
(a) Is the point (2,8) on the graph of f?
(b) If x= -1, what is f(x)? What point is on the graph of f?
If f(x) = -2, what is x? What point(s) are on the graph of f?
(d) What is the domain of f?
(c)
(e) List the x-intercept(s), if any, of the graph of f.
(f) List the y-intercept, if there is one, of the graph of f.

Answer 1

Explanation:

f(x)=3x²-x-2

a) (2,8)

f(2)=3(2²)-2-2

f(2)=3(4)-4

f(2)=12-4

f(2)=8

Hence, the point (2,8) is on the graph of f(x)

b) x=-1

f(-1)=3((-1)²)-(-1)-2

f(-1)=3(1)+1-2

f(-1)=3-1

f(-1)=2

c) x=-2

f(-2)=3((-2)²)-(-2)-2

f(-2)=3(4)+2-2

f(-2)=12+0

f(-2)=12

`d)\ f(x)\in(-2(1)/(12) ,\infty)`

e) y=0

3x²-x-2=0

3x²-x-2=0

3x²-3x+2x-2=0

3x(x-1)+2(x-1)-0

(x-1)(3x+2)=0

x-1=0

x=1

3x+2=0

3x=-2

Divide both parts of the equation by 3:

x=-2/3

f) x=0

f(x)=3(0²)-0-2

f(x)=3(0)-2

f(x)=0-2

f(x)=-2