Math help Please!!!?

Question

Given the function f(x) = x2 - 6x + 8, find x, if f(x) = 0.

A. 4 and 2
B. -4 and -2
C. 8 and 4
D. -8 and -4

2. Given the function f(x) = x2 - 6x + 8, find x, if f(x) = 3.

A. 4 and 2
B. -4 and -2
C. 1 and 5
D. -1 and -5


3. Given the function f(x) = x2 - 6x + 8, find f(0).

f(0) = ____

A. 0
B. 2
C. 4
D. 8


4. Given the function f(x) = x2 - 6x + 8, find f(-2).

f(-2) = ____

A. -6
B. 6
C. 10
D. 24

Answer 1

1.f(x)=0
which means x2-6x+8=0
so, factorize the equation u'll get (x-4)(x-2)=0
therefore, x-4=0-->x+4
x-2=0-->x=2
the answer is A
2.f(x)=3
means x2-6x+8=3
x2-6x+8-3=0
x2-6x+5=0
factorize the equation u'll get (x-5)(x-1)=0
so,x=5,1
the answer is C
3. f(x)=x2-6x+8
f(0), substitute x=0
so f(0)= (0)2-6(0)+8
=8
the ans is D
4.f(-2), substitute x=-2
so, f(-2)= (-2)2-6(-2)+8
=24
the ans is D

Answer 2

1. First we take the first function:

f(x) = x2 - 6x + 8

And set it equal to zero:

0 = x^2 - 6x + 8

Now we have to decide what adds up to -6 and multiplies to get 8, It seems that -4 and -2 are good for this, now we factor:

0 = (x - 4)(x - 2)

So x = 4 and 2

1 = A

2. Now we do the same thing as before, but set it equal to 3 instead:

3 = (x - 4)(x - 2)

Now we split each factor and set it equal to 3:

3 = x - 4

x = 7

3 = x - 2

x = 5

x = 7 and 5

2 = I have no idea... But those are the answers... So I guess C because it has a positive 5.

3. For this all we do is plug every x-value with whatever value is given:

f(x) = x2 - 6x + 8

f(0) = 0^2 - 6(0) + 8

f(0) = 8

3 = D

4. Same thing here:

f(x) = x2 - 6x + 8

f(-2) = (-2)^2 - 6(-2) + 8

= 4 + 12 + 8

= 24

4 = D

And there you go.

Answer 3

Answer 1:
f(x) = x^2 - 6x + 8
f(x) = 0

So,
x^2 - 6x + 8 = 0
x^2 - 4x - 2x + 8 = 0
x(x - 4) - 2(x - 4) = 0
(x - 4)(x - 2) = 0
x = 2, 4

The answer is (A) 4 and 2


Answer 2:
f(x) = x^2 - 6x + 8
f(x) = 3

So,
x^2 - 6x + 8 = 3
x^2 - 6x + 5 = 0
x^2 - x - 5x + 5 = 0
x(x - 1) - 5(x - 1) = 0
(x - 5)(x - 1) = 0
x = 1, 5

The answer is (C) 1 and 5.


Answer 3:
f(x) = x^2 - 6x + 8 ------------------- (1)

To find f(0) Just put x = 0 in the Right Hand Side (RHS) of (1)

f(0) = 0^2 - 6(0) + 8
= 8

The answer is (D) 8


Answer 4:
f(x) = x^2 - 6x + 8

Using the method above,
f(-2) = (-2)^2 - 6(-2) + 8
= 4 + 12 + 8
= 24

The answer is (D) 24.

Answer 4

is this your homework?

i'll give you the answer, try and solve it yourself!

1)A
2)C
3)D
4)D

if its not homework, email me.. i'll tell u how to solve. but i am sure.. someone else will post here and tell u how to solve it