math [ i need help with these.]
posted by margiee (: ! .
2. 2x(x+3)=0
2x^2+3x=0
[i don't know what to do.]
3. y^2+8y=0
4. x^2+3x=28
5.2x^2+9x5=0
2x^2+9x=5
[please help me by starting off the problems, or explaining for each.]

2. 2x(x+3)=0
There are 2 terms: 2x and (x+3).
If any term in a product is 0 the whole product is 0. So, what value of x would make 2x=0 and what value of x would make x+3 = 0? 
x=3 ?

Sorry, I meant to say factor not term.
If any "factor" in a product is 0 the whole product is 0.
There are 2 "factors". 
i still don't understand , i'm sorry .

2x(x+3)=0
I am assuming that you need to find the values of x that will be true for the above.
When you multiply several items (each of these is called a factor) together the answer (called the product) is 0 if ANY of them are 0.
Example:
multiply (a)(b)(c)
If any of them, a or b or c is 0, then multiplying them always gives 0.
The problem has 2 factors:
2x
(x+3)
If either of these is 0 then 2x(x+3) is 0.
The answers are 0 and 3.
It is always a good idea to substitute back to check.
For x=0
2x(x+3)
=2(0)(0+3)
0(3)
=0
For x=3
2(3)(3 + 3)
=(6)(0)
=0 
The line
0(3)
should have been
=0(3)
See below:
For x=0
2x(x+3)
=2(0)(0+3)
=0(3)
=0 
Aren't you supposed to solve these equations for x?
For #2, if
2x(x+3)=0, then either x = 0 or x = 3 will satisfy equation. Those are the solutions,
For #4, note that x^2 + 3x  28 =
(x+7)(x4). Since this is zero, then x = 7 and x = 4 satisfy the original equation, and are solutions
The two equations that you wrote for #5 are inconsistent. If the first one is correct, then what you need to do is factor 2x^2+9x5
Try (2x1)(x+5)
If that equals zero, then either factor is zero, and that tells you what x is. 
mkay , thanks (:
so , what about number 3 ? 
Factor y^2 + 8y = 0 into
y(y+8) = 0, and get the solutions from the factors. We are trying to teach you how to do these by yourself.
Respond to this Question
Similar Questions

Math
My friend and I are both going to start working. I'm starting Sunday and will have every 9th day off. She's starting Monday (the day after me) and will have every 6th day off. When is the first day we'll both have off to go to the … 
Chemistry
Okay, in this prolem i need to balence this equation. Even our teacher had problems with it, but he refuses to help anyone. PbCrO4 + HCL + FeSO4 > PbCl2 + Cr2 (SO4)3 + H2O + Fe2(SO4)3 please help me. this is the last problem … 
Math
how do you do these problems?? 526 22/9 82/3 4/3+6 But I can do these types pf problems ( don't need help with problems below) 3/4 + 1/10 and 5/6  1/4 Please Help!! Thanks!!! 
Math Help please!!
how do you do these problems?? 526 22/9 82/3 4/3+6 But I can do these types pf problems ( don't need help with problems below) 3/4 + 1/10 and 5/6  1/4 Please Help!! Thanks!!! 
english
i starting to write a descriptive story and i have to switch on and off from reality like in Walter Mitty story. so I think of writing about childhood having flashbacks of past. but i not know how starting it off. 
Math
The sunglasses that Ramon wants to buy are 50% off the original price of $85. If he has to pay 6% tax, what will the glasses cost? 
Math
I need help to set the equation up to solve a system to ensure that I get the answer of (2, 4)? 
Math 222
I am starting to wonder why when I ask for help with my math problems, I get skipped over? 
algebra
A student missed 11 problems on a Chemistry test and received a grade of 65%. If all the problems were of equal value, how many problems were on the test? 
algebra homework help
student missed 11 problems on a Chemistry test and received a grade of 65%. If all the problems were of equal value, how many problems were on the test?