Question

am i correct on this?

I CHOSE B
4. What is the solution set to the equation 2a2 + 8a = 0?
(Points : 1)
{2, 4}

{0, 4}

{0, -4}

{-4,- 4}

Answer 1

I did not get option B. Let me check my work.

Answer 2

i tried factoring like in the lesson then i just filled them in, i may be missing something again

Answer 3

@IDAREYOU If you substitute 4 back into this --> 2a2 + 8a = 0 you will not get zero.

Answer 4

i didnt get B either, but B is the second best answer!

Answer 5

even with -4?

Answer 6

@IDAREYOU Will you consider posting your factoring?

Answer 7

If this option is B {0, 4}, where is the -4? :)

Answer 8

2a^2 +8a = 0
8a = 2 x 4 right?

Answer 9

2a(a + 4) = 0
2a = 0 or a + 4 = 0
a = ? or a = ?

Answer 10

@IDAREYOU

Do you follow the factoring I did? I used the distributive property and then the zero product property.

Answer 11

@IDAREYOU the answer is C.
because when you put in 0=a you get the rhs to be a zero
and when you put in a=-4 you get rhs to be a zero
hence the option is C

Answer 12

0/ 2 = 0 and a + 4 = 0 = a = 0 - 4 = a = -4

Answer 13

do you want more work?

Answer 14

@croslali Yes, we believe in work to support answers.

Answer 15

@IDAREYOU

2a(a + 4) = 0
2a = 0 or a + 4 = 0
a = 0 or a = -4

Yes, you completed that correctly. Suggestion: Be systematic with your work. It will pay off.

Answer 16

so if i check it:

2(-4)^2 + 8(-4) = 0

2 x 16 = 32
8 x -4 = -32

32 - 32 = 0

i wasn't using the ()

Answer 17

That is half the checking.

Answer 18

i jumped ahead of myself on this one

Answer 19

Right. There is no prize for finishing first so be systematic.

"Fast is fine but accuracy is everything." ~ Wyatt Earp

Answer 20

2(0)^2 + 8(0)

2 x 0 + 8 x 0
0 + 0 = 0

Answer 21

Yes. That's the way to do these.

Answer 22

ok, so when factoring its just the GCF?

Answer 23

On that particular problem, yes.

On something like: x^2 + 5x - 6 = 0, then that is not what I think of as a GCF problem.

Answer 24

so on this my gcf would be 10 thus i would have

x = 0 x+5 = 0?

5. What is the solution set to the equation x2 + 10x = 21?
(Points : 1)
{3, 7}

{-21,- 31}

{0, -10}

{-3, -7}

Answer 25

oh wait that should be brought over like they showed so i would subtract or add 21 to both sides

Answer 26

There is no GCF here that I see. This is factoring a trinomial.

x2 + 10x = 21

x^2 + 10 x - 21 = 0

Answer 27

do you have microsoft word so you can see how they are showing it in my lesson?

Answer 28

@IDAREYOU Check and see if you posted the problem correctly.

None of the options fit this: x2 + 10x = 21

Answer 29

its a -21

Answer 30

x2 + 10x = -21

Answer 31

I can read Word documents.

Answer 32

x2 + 10x = -21

x2 + 10x + 21 = 0

(x + ?)*(x + ?) = 0

Answer 33

(x + 10) (x + 21) or (x + 5) (x + 7)

Answer 34

(x + 10) (x + 21) = x^2 + 31x + 210 so that's not it.

(x + 5) (x + 7) = x^2 + 12x + 35 so that's not it.

Answer 35

x2 + 10x + 21 = 0

What are two numbers that multiply to 21 AND also add to 10 ?

Answer 36

@IDAREYOU

Answer 37

3 X 7 = 21
7 + 3 = `10

Answer 38

x2 + 10x + 21 =

x^2 + 7x + 3x + 21 =

x* (x + 7 ) + 3* (x + 7) =

(x + 7) * (x + 3)

Answer 39

x2 + 10x + 21 = 0
(x + 7) * (x + 3) = 0
(x + 7) = 0 OR (x + 3) = 0

x = ? or x = ?

Answer 40

x = 0 - 7 x = 0 - 3

Answer 41

Yes. And, then x = -7, x = -3

Answer 42

x = -7 x = 3 [-7,-3}

Answer 43

i have 2 more quizzes to take before i win this bet with my dad

Answer 44

x = -7 x = 3 [-7,+3} --> You had a bad sign on the 3.

Answer 45

um wait 3, - 7

Answer 46

I don't understand how this came about:

x = -7 x = 3 [-7,-3}

Answer 47

x = -7, x = -3

Answer 48

3 x 3 = 9 + 10 x 3 = 30

9 + 30 = 39

not 21

thats why i had a negative

Answer 49

but -7 x -7 = 49 + 10 x -7 =-70

49 + -70 = -21 like in the original problem

Answer 50

two numbers that multiply to 21 AND also add to 10 are 7 and 3. They are not the solutions to the equation. They are numbers that figure into the factoring through which you get the solutions to the equation.

Answer 51

yes but after i solve for zero x + 7 = 0 and x + 3 = 0

Answer 52

i mean solve for x

Answer 53

Then, you get -7 and -3 as solutions to the equation.

Answer 54

and that where i got (-7,-3) :)

Answer 55

Right. Seriously, you should work to get a grip on this factoring. It will follow you in problems for the next 3 years at least.

Answer 56

Thank you

Answer 57

You are welcome.