Questions on Algebra: Linear Algebra (NOT Linear Equations) answered by real tutors!

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Question 163304: x(x-2)=4: x(x-2)=4
Answer by jojo14344(1029) About Me  (Show Source):
You can put this solution on YOUR website!
x(x-2)=4
x^2-2x=4
x^2-2x-4=0
Remember: a=1,b=-2, c=-4
By Pyth. theorem:
x=(-b+-sqrt(b^2-4ac))/(2a)
x=(-(-2)+-sqrt(-2^2-4*1*-4))/(2*1)
x=(2+-sqrt(4+16))/2
x=(2+-sqrt(20))/2
2 values:
x=(2+sqrt(20))/2=(2+4.472136)/2=6.472136/2
highlight(x=3.236068)
x=(2-sqrt(20))/2=(2-4.72136)/2=-2.472136/2
x=-1.236068
Check it out,x=3.236068
3.236068(3.236068-2)=4
3.236068(1.236068)=4
4.000000001=4 close enough! bec of decimals
Thank you,
Jojo
Question 163304: x(x-2)=4: x(x-2)=4
Answer by Fombitz(1798) About Me  (Show Source):
You can put this solution on YOUR website!
x(x-2)=4
x^2-2x=4
x^2-2x-4=0
Use the quadratic formula,
x = (-b +- sqrt( b^2-4*a*c ))/(2*a)
x = (-(-2) +- sqrt( (-2)^2-4*1*(-4) ))/(2*1)
x = (2 +- sqrt( 4+16 ))/(2)
x = (2 +- sqrt(20 ))/(2)
or approximately
x[1]=(2+4.47)/2=3.235
x[2]=(2-4.47)/2=-1.235