## anonymous one year ago Solve each quadratic equation. Show your work Where do i start? 4x^2 = 100

1. welshfella

divide both sides by 4 to isolate x^2:- x^2 = 25 can you continue?

2. anonymous

that will give the answer right

3. welshfella

well you need to find the value of x x ^2 means x times x so you need to think of a number which when multiplied by itself gives 25 ?

4. anonymous

Okay. 4x^2/4 100/4 = 25

5. anonymous

Does that get rid of the x^2?

6. anonymous

the work shown should help get the solution which i think is 25

7. anonymous

Yeah 100/4=25

8. anonymous

Do i have x^2 any more or does it go with the 4 @welshfella ?

9. welshfella

no 25 is not the solution we have x^2 = 25 so x = ?

10. anonymous

11. anonymous

25x^2?

12. anonymous

100 is the solution

13. anonymous

x=4

14. welshfella

no the solution is the value of x we know that x times x = 25 so what must x be?

15. welshfella

Not 4 because 4*4 = 16 not 25

16. anonymous

what do you think

17. anonymous

How do we find the value of x?

18. welshfella

x is the square root of 25 that is the number that when multiplied by itself gives 25 for example 3 is square root of 9 as 3 * 3 = 9

19. anonymous

hold on let me try to figure this out

20. welshfella

what times what = 25?

21. anonymous

so you would use square root

22. welshfella

yea

23. anonymous

okay

24. anonymous

625?

25. anonymous

i think so

26. welshfella

no - thats the SQUARE of 25 25*25 = 625

27. anonymous

okay what do you think

28. welshfella

5 *1 = 5 5*2 = 10 5*3 = 15 5*4 = 20 what comes next?

29. welshfella

now you have it

30. anonymous

25

31. anonymous

sooooo

32. welshfella

5 is the square root of 25 because 5 * 5 = 25 x^2 = 25 so x = 5

33. anonymous

Alright

34. welshfella

actually there is 2 answers 5 and -5 because -5*-5 is also equal to 25

35. anonymous

okay was i right

36. anonymous

Neat. Thanks for helping me i appreciate it :)

37. welshfella

@kitty_lover1234 No . 25 is not the answer

38. anonymous

what do you think it is

39. anonymous

x=5

40. anonymous

okay

41. welshfella

also -5 write the answer as {5,-5}

42. anonymous

Alright

43. welshfella

that is what is known as the 'solution set'. Written in curly brackets.

44. anonymous

i see where i went wrong