## ThisShouldFeelLikeFire 3 years ago How exactly do I solve this equation? x2 - 12x = -36

1. kevsturge

$x^2-12x+36=0$ now solve the quadratic

2. kevsturge

gives x=6 can yuo see why

3. precal

you can use the quadratic formula or you can factor it you can also, look at its graph and see where it crosses the x axis

4. kevsturge

here yuo can factor the eqn, Do you know how to do this?

5. ThisShouldFeelLikeFire

I don't understand how you got x = 6...

6. precal

|dw:1338677027789:dw|

7. precal

|dw:1338677062779:dw|

8. ThisShouldFeelLikeFire

I'm sorry... I'm so confused. /:

9. ThisShouldFeelLikeFire

Oh! Wait I think I get it!!

10. ThisShouldFeelLikeFire

Took me a little bit :P Thank you both a ton!!

11. kevsturge

if you factorise the equation you get (x-6)(x-6) so when (x-6)=0 x=6 Do you see

12. kevsturge

Here is how I practice factorising write the factorised end point i.e. (x+3)x+4) and expand the brackets to give$x^2+4x+3x+12 \rightarrow x^2+7x+12$ now |I take $x^2+7x+12$ and work backwards because I know it will definitely factorise

13. precal

|dw:1338678477379:dw|

14. precal

|dw:1338678551861:dw|

15. kevsturge

wow that's the hard way! but it does always work. Try to factorise it before going through all this stress

16. precal

just presenting multiple ways to solve it. Quadratic formula works 100% of the time, factoring does not

17. kevsturge

that's what I said :P