SOLUTION: find the solution of x^2-21=4x. if the solution is a fraction, enter it in simplest form?

Question 192104: find the solution of x^2-21=4x. if the solution is a fraction, enter it in simplest form?
Found 2 solutions by checkley75, RAY100:
Answer by checkley75(3666) (Show Source): You can put this solution on YOUR website!
x^2-21=4x
x^2-4x-21=0
(x-7)(x+3)=0
x-7=0
x=7 ans.
x+3=0
x=-3 ans.
Answer by RAY100(1637) (Show Source): You can put this solution on YOUR website!
x^2-21=4x
subt 4x each side
x^2-4x-21=0
FACTOR
(x+3)(x-7)=0
set (x+3)=0, x=(-3)
set (x-7)=0, x=(7)
check
(-3)^2-21=4(-3)
9-21=-12 ok
(7)^2-21=4(7)
49-21=28 ok
RELATED QUESTIONS
find the solution of x^2-21=4x. if the solution is a fraction, enter it in simplest form (answered by josmiceli)
find the solution of x^2+4x+4=0. if the solution is a fraction enter it in simplest form. (answered by jojo14344)
Find all real solutions of the equation. (Enter your answers as a comma-separated list.... (answered by ewatrrr)
Not sure how to type them in but the bracket is suppose to connect both numbers in one... (answered by addingup,ikleyn,MathTherapy)
Solve the system using any method. (Simplify your answer completely. If the system is... (answered by MathLover1,MathTherapy)
Solve the system using any method. (Simplify your answer completely. If the system is... (answered by solver91311)
Line l passes through (21,-3) and line p is the graph of 7x-4y=13 If what is the... (answered by ankor@dixie-net.com)
Find all real solutions of the equation. (Enter your answers as a comma-separated list.... (answered by Fombitz)
Find the exact solution, using common logarithms. (Enter your answers as a... (answered by Theo,MathTherapy)