quadratic formual of x^2-4x-5=0 show work
qudratic equation of X^2-4x-5=0 show work
2006-11-25 01:48:49 · 6 answers · asked by csmitty 1 in Science & Mathematics ➔ Mathematics
x={-(-4) (+/-)√[(-4)^2 - 4(1)(-5)]}/(2(1))
x= 4(+-)6/2
x=5, x=-1
Check:
with x=5, 5^2-4(5)-5=25-20-5=0 OK
with x=-1 (-1)^2 -4(-1) -5 = 1+4-5=0 OK
2006-11-25 02:03:52 · answer #1 · answered by albert 5 · 0⤊ 0⤋
using the formula :
x^2-4x-5=0
a=1,b=-4,c=-5
x=[-b+(b^2-4ac)^1/2]/2a
puting values :
x=[4+/-rt(16+20)]/2
x =(4+/-6)/2
x =4+6/2=5
x =4-6/2=-1
therefore x=+5,-1
using eqn
x^2 - 5x +x -5=0
x(x-5)+1(x-5)=0
(x+1)(x-5)=0
x=-1,+5
thanks good luck
2006-11-25 02:02:32 · answer #2 · answered by sidharth 2 · 0⤊ 0⤋
x^2-4x-5=0
(x-5)(x+1)=0
x-5 =0 so, x=5
x+1 =0 so, x=-1
Using quadratic formula is much mor cumbersome than factoring. You shoul use it whenever possible to save time.
2006-11-25 01:57:05 · answer #3 · answered by ironduke8159 7 · 0⤊ 0⤋
x2 - 4x -5 = (x-5)(x+1)
x - 5 (cross multiply, x time -5 and x time 1) -5x
x + 1 + x
x2 - 5 -4x
2006-11-25 01:54:09 · answer #4 · answered by Failure 2 · 0⤊ 0⤋
x^2-4x-5=0
a=1,b=-4,c=-5
x=[-b+/-rt(b^2-4ac)]/2a
sub
x=[4+/-rt(16+20)]/2
=(4+/-6)/2
=4+6/2=5
=4-6/2=-1
2006-11-25 01:51:46 · answer #5 · answered by raj 7 · 0⤊ 0⤋
it comes down as (4 + or - SR of 6) / 2
Where x = 5 and -1
2006-11-25 02:00:41 · answer #6 · answered by Anonymous · 0⤊ 0⤋