Question

Solve \[\sqrt{x-5} +7 =x\]

Answer 1

x=9

Answer 2

i have x = -9

Answer 3

it can't be that.
this is because suare roots can't have negative values.

Answer 4

root (x - 5) + 7 = x
root (x - 5) = x - 7
x - 5 = (x - 7)^2
x - 5 = x^2 - 14x + 49
0 = x^2 -15x + 54
0 = (x-9)(x-6)
x = 9 and 6

Answer 5

x = -9 can't be right as the term under the square root would then be negative.

Answer 6

jbell and saifoo, you are missing 6.

Answer 7

ohhh i see my mistake! thanks guys! :)

Answer 8

cow, no you are writing it wrong. LOL.

Answer 9

and no i have x = 6

Answer 10

what you will do with \[\sqrt{1}\]??

Answer 11

what \[\sqrt{1}\]?

Answer 12

This is a nice problem, showing how squaring things can introduce new possibilities that don't satisfy the original equation.

It's clear that x = 6 does not satisfy the equation; but it snuck in here because we squared the sqrt(x-5) term.