Question

RADICAL EQUATIONS
-4√(x+9) = 20

(That is read at -4 times the square root of x+9 equals 20)

Answer 1

16

Answer 2

root(x + 9) = 20/-4
root(x + 9) = -5
squaring both sides
x + 9 = 25
x = 25-9
x = 16

Answer 3

Thats what I got when I did it but then I checked it and it didn't fit? When I checked it I got -5 ≠ 5.

Answer 4

√(x+9)=-5
Square it x+9=25 so x=16

Answer 5

@juicylovexx
the checking works out
root(x + 9) = 20/-4
root(x + 9) = -5
now put x = 16 and u get
root(16 + 9) = -5
root(25) = -5
+/- 5 = -5

so -5 = -5

see
5² = 25 so root(25) = 5
also
(-5)² = 25 s0 root(25) = -5

Answer 6

Thank you! I get it now.

Answer 7

That's not right harkirat. the square root is always positive. So this equation has no real solutions, I'm not sure about imaginary solutions.

Answer 8

@Thomas9
when solving quadratic equations, we calculate

+/- root(b² - 4ac)

why do we take +/- values there????

Answer 9

Yeap, no solutions exist

Answer 10

That doesn't make the square root negative.

http://www.wolframalpha.com/input/?i=solve+-4sqrt%28x%2B9%29%3D20

Answer 11

http://www.wolframalpha.com/input/?i=-4%E2%88%9A%28x%2B9%29+%3D+20

Answer 12

so there is no solution?...