SOLUTION: I need help learning how to work the quadratic equations from beginning to end and knowing how to find the right numbers that go in the equations. For example; {{{ x2 - 2x - 13 =

Algebra ->  Quadratic Equations and Parabolas -> SOLUTION: I need help learning how to work the quadratic equations from beginning to end and knowing how to find the right numbers that go in the equations. For example; {{{ x2 - 2x - 13 =      Log On


   

Question 626473: I need help learning how to work the quadratic equations from beginning to end and knowing how to find the right numbers that go in the equations. For example;
+x2+-+2x+-+13+=+0+
Thank you for your time,
Markana
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
x%5E2-2x-13=0 Start with the given equation.


Notice that the quadratic x%5E2-2x-13 is in the form of Ax%5E2%2BBx%2BC where A=1, B=-2, and C=-13


Let's use the quadratic formula to solve for "x":


x+=+%28-B+%2B-+sqrt%28+B%5E2-4AC+%29%29%2F%282A%29 Start with the quadratic formula


x+=+%28-%28-2%29+%2B-+sqrt%28+%28-2%29%5E2-4%281%29%28-13%29+%29%29%2F%282%281%29%29 Plug in A=1, B=-2, and C=-13


x+=+%282+%2B-+sqrt%28+%28-2%29%5E2-4%281%29%28-13%29+%29%29%2F%282%281%29%29 Negate -2 to get 2.


x+=+%282+%2B-+sqrt%28+4-4%281%29%28-13%29+%29%29%2F%282%281%29%29 Square -2 to get 4.


x+=+%282+%2B-+sqrt%28+4--52+%29%29%2F%282%281%29%29 Multiply 4%281%29%28-13%29 to get -52


x+=+%282+%2B-+sqrt%28+4%2B52+%29%29%2F%282%281%29%29 Rewrite sqrt%284--52%29 as sqrt%284%2B52%29


x+=+%282+%2B-+sqrt%28+56+%29%29%2F%282%281%29%29 Add 4 to 52 to get 56


x+=+%282+%2B-+sqrt%28+56+%29%29%2F%282%29 Multiply 2 and 1 to get 2.


x+=+%282+%2B-+2%2Asqrt%2814%29%29%2F%282%29 Simplify the square root (note: If you need help with simplifying square roots, check out this solver)


x+=+%282%29%2F%282%29+%2B-+%282%2Asqrt%2814%29%29%2F%282%29 Break up the fraction.


x+=+1+%2B-+sqrt%2814%29 Reduce.


x+=+1%2Bsqrt%2814%29 or x+=+1-sqrt%2814%29 Break up the expression.


So the solutions are x+=+1%2Bsqrt%2814%29 or x+=+1-sqrt%2814%29

--------------------------------------------------------------------------------------------------------------
If you need more help, email me at jim_thompson5910@hotmail.com

Also, please consider visiting my website: http://www.freewebs.com/jimthompson5910/home.html and making a donation. Thank you

Jim
--------------------------------------------------------------------------------------------------------------