katlin95
solve for x: sqrt x^2-x-5=5
A. -5
B. -6
C. 6
D. -5, 6
Delete
Share
This Question is Closed
katlin95
Best Response
You've already chosen the best response.
0
|dw:1365027513803:dw|
cwrw238
Best Response
You've already chosen the best response.
0
your question isa bit confusing
do you mean square root
oh ok
phi
Best Response
You've already chosen the best response.
0
what do you get if you square both sides of the equation ?
katlin95
Best Response
You've already chosen the best response.
0
not sure..
phi
Best Response
You've already chosen the best response.
0
how about the right side of the = sign ? what is 5*5 ?
katlin95
Best Response
You've already chosen the best response.
0
25
phi
Best Response
You've already chosen the best response.
0
on the left use the rule that a sqrt times itself makes the square root "go away"
in other words, sqrt(x) * sqrt(x) is x no matter how complicated x is.
katlin95
Best Response
You've already chosen the best response.
0
-6
phi
Best Response
You've already chosen the best response.
0
All we want is the left side squared.
here are some examples
sq rt(1+2+3)* sq rt (1+2+3) = 1+2+3
or
sq rt(x^2 * 30y)* sq rt (x^2*30y) = x^2*30y
what is
sq rt (x^2-x-5) * sq rt (x^2-x-5) ?
phi
Best Response
You've already chosen the best response.
0
do you need more examples of what happens when you square a square root ?
katlin95
Best Response
You've already chosen the best response.
0
no:)
phi
Best Response
You've already chosen the best response.
0
in that case what is
sq rt (x^2-x-5) * sq rt (x^2-x-5) ?
katlin95
Best Response
You've already chosen the best response.
0
-5,6
phi
Best Response
You've already chosen the best response.
0
I have not solved this, so I don't know off hand. You can learn to solve it
or you can try substituting in possible answers and see if they work.