## anonymous 5 years ago √(x+16)=x+4

1. anonymous

$\sqrt{x+16}=x+4$

2. anonymous

square both sides x+16=(x+4)^2 (x+4)^2 is the same as (x+4)(x+4)= x^2+8x+16 x+16=x^2+8x+16 subtract both sides by 16 x=x^2+8x subtract both sides by x 0=x^2+8x-x 8x-x=7x 0=x^2+7x Factor out an x 0=x(x+7) Now you have to find at what value of x the equation is equal to 0. The obvious one is x=0 because: 0*(0+7) is 0 The other one is x=(-7) -7*(-7+7)=-7*(0)=0 So x= -7, 0

3. anonymous

whoa, are you wearing a bra

4. anonymous

x=0 is correct. Radical 16 = 4. at x=-7, 3 radical 9 is not equal to -3

5. anonymous

6. anonymous

wait WHAT?

7. anonymous

There is no negative sign, explicit or inferred as far as I can see, in front of the radical sign in your problem statement. If you replace x with -7 in your problem equation and do the math, you will get on the left hand side, $\sqrt{-7+16}=3$ On the right and side you will get -7+4=-3. 3 is unequal to -3. In other words -7 is not a solution to the problem as presented.