# Equations/Functions

#### davehogan

##### New member
Some simple equations mystify me. I am asked to sketch the following function on a graph. "f(x)=(x-2)2(x+1)", but I can't get this right. The answer shows a cubic graph and it goes from 2,0 to 0,4 then down to -1, 0. now I understand this except the move to 0,4. I know that -22 is 4, but that is just dealing with first term (x-2)2. Then we go on with the next term (x+1). I'm really confused with this.

#### lookagain

##### Senior Member
Some simple equations mystify me. I am asked to sketch the following function on a graph.
"f(x)=(x-2)2(x+1)", but I can't get this right. The answer shows a cubic graph and it goes from 2,0 to 0,4 then down to -1, 0.
now I understand this except the move to 0,4. I know that -22 is 4, but that is just dealing with first term (x-2)2.
Then we go on with the next term (x+1). I'm really confused with this.
What are you doing typing coordinates without the required parentheses!? And why do you think -22 is 4? It's supposed to be (-2)2 = 4. $$\displaystyle \ \$$ <----Edit

Type all of your coordinates using parentheses.

The y-intercept is where x = 0. $$\displaystyle \ \ f(0) \ = \ (0 - 2)^2(0 + 1) \ = \ (-2)^2(1) \ = \ (4)(1) = 4$$

So, the y-intercept is (0,4).

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#### srmichael

##### Full Member
Some simple equations mystify me. I am asked to sketch the following function on a graph. "f(x)=(x-2)2(x+1)", but I can't get this right. The answer shows a cubic graph and it goes from 2,0 to 0,4 then down to -1, 0. now I understand this except the move to 0,4. I know that -22 is 4, but that is just dealing with first term (x-2)2. Then we go on with the next term (x+1). I'm really confused with this.
The way you wrote your question is a little confusing. When you say "...it goes from 2,0 to 0,4 then down to -1, 0" I assume you are referring to the coordinates (2,0), (0,4), and (-1,0). These are simply the x and y intercepts. Do you know how to find the x and y intercepts of a function?

#### davehogan

##### New member
What are you doing typing coordinates without the required parentheses!? And why do you think -22 is 4? It's supposed to be (-22) = 4.

Type all of your coordinates using parentheses.

The y-intercept is where x = 0. $$\displaystyle \ \ f(0) \ = \ (0 - 2)^2(0 + 1) \ = \ (-2)^2(1) \ = \ (4)(1) = 4$$

So, the y-intercept is (0,4).

I obviously need to revise on coordinates. I tried (x=-2) and came up with (-16) which is clearly wrong. Thanks for explaining the coordinates (0,4).

#### HallsofIvy

##### Elite Member
What are you doing typing coordinates without the required parentheses!? And why do you think -22 is 4? It's supposed to be (-22) = 4.

Actually, no. $$\displaystyle (-2^2)= -4$$. What you mean is $$\displaystyle (-2)^2= 4$$.

Type all of your coordinates using parentheses.

The y-intercept is where x = 0. $$\displaystyle \ \ f(0) \ = \ (0 - 2)^2(0 + 1) \ = \ (-2)^2(1) \ = \ (4)(1) = 4$$

So, the y-intercept is (0,4).