How do you solve #9x² + 42x = -49#?

Question

2687 views around the world

You can reuse this answer
Creative Commons License

Answer 1 · 2018-06-06T17:10:42

#x = -7/3#

#9x^2 + 42x = -49#

Move all terms to LHS

#9x^2 + 42x + 49 = 0#

Now we factor

#(3x+7)(3x+7) = 0#

#(3x+7)^2 = 0#

Now we solve for #x#

#3x+7 = 0#

#3x = -7#

#x = -7/3#

Although this is a polynomial of degree #2# and you would expect #2# solutions, it turns out that there is one redundant solution, namely #x = -7/3#.