## Makayla43 3 years ago Solve by factoring. 4x2 + 23x + 15 = 0

1. timo86m

ooh i like these

2. freckles

\[ax^2+bx+c=0\] So what you want to do is find factors of a*c that have product a*c and sum b.

3. timo86m

(x+5)*(4*x+3)

4. Makayla43

Good! Can you help me?

5. freckles

find two factors*

6. freckles

So what is a here? And what is b here? And what is c here?

7. Makayla43

\[4x ^{2}+23x+15=0\]

8. timo86m

(x+5)*(4*x+3) x= -5 and -3/4 right

9. freckles

@timo86m I don't think it helps to give the answer. Can you explain how you got those factors?

10. Makayla43

A:x = 0.8 or x = -0.75 C:x = 0.75 or x = 5 B:x = -3 or x = -1.25 D:x = -0.75 or x = -5

11. freckles

@Makayla43 if you want to learn this, I'm trying to teach you.

12. freckles

What is a,b, and c in your equation?

13. Makayla43

@KNicksfan4life :D (:

14. KNicksfan4life

(4x-3)(x-5)

15. Makayla43

@freckles what do you mean a,b,and c?

16. KNicksfan4life

is that rite

17. timo86m

it not right

18. freckles

\[ax^2+bx+c=0\] \[4x^2+23x+15=0\]

19. timo86m

(x+5)*(4*x+3) if you not sure you can always expand this

20. Makayla43

Solve by factoring. -3x2 - x + 2 = 0

21. timo86m

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

22. Makayla43

\[-3x ^{2}-x+2=0\]

23. timo86m

-3x2 - x + 2 = 0 you actually mean -3x^2 - x + 2 = 0

24. Makayla43

A:x = 0.5 or x = 0.33333 C:x = 1 or x = -0.66667 B:x = 0.33333 or x = -2 D:x = -1 or x = 0.66667

25. timo86m

I think it d

26. myininaya

You guys how is this teaching and how is this learning? Please try to teach @Makayla43 and not just give the answer. And @Makayla43 you shouldn't be just looking for answers. I think freckles here was trying to teach you how to do this.

27. Makayla43

Omg.

28. timo86m

i teached, I said expand my factor if she doubts it lol.

29. myininaya

But @timo86m how do you get the factors? Please explain that part so she will know how to do it.

30. Makayla43

Goodbye. He sent me a message a explained.

31. timo86m

4x2 + 23x + 15 = 0 number that up to 15 and product is 23

32. timo86m

To factor is mostly guess work that is where I draw the line :)

33. timo86m

number that up to c and product is b coefficient. It is more important to show why it works then how to do something that is mostly guess work.