completing the square - equations?

0 ⤊

anybody?
Use the method of completing the square to solve x^2 - 10x = 15
Give your answer in the form p ±k√q where p, k and q are rational

thank you

2007-03-05 03:58:01 · 3 answers · asked by me m 1 in Science & Mathematics ➔ Mathematics

x^2-10x=15
=>x^2-2*x*5+(5)^2=15+25 [adding 5^2 or 25 to both sides]
=>(x-5)^2=40
x-5=+-sqrt40=+-2sqrt10
=>x=5+-2sqrt10

2007-03-05 04:13:13 · answer #1 · answered by alpha 7 · 0⤊ 0⤋

xÂ²-10x=15
xÂ²-10x+25=40
(x-5)Â²=40
x-5=Â±2â10
x=5Â±2â10

2007-03-05 12:02:16 · answer #2 · answered by Pascal 7 · 0⤊ 0⤋

x^2-10x-15= (x-5)^2 -40 so x= 5+-sqrt(40)=5+-2sqrt(10)

2007-03-05 12:06:51 · answer #3 · answered by santmann2002 7 · 0⤊ 0⤋