How do you solve $3x^2+14x=5$ by completing the square?

Question

2206 views around the world

You can reuse this answer
Creative Commons License

Answer 1 · 2015-05-12T19:08:16

Dividing through by $3$ , we get:

$x^2+(14/3)x = 5/3$

Now try squaring $x+7/3$

$(x+7/3)^2 = (x+7/3)(x+7/3)$

$= x^2 + (14/3)x + 49/9$

$= 5/3 + 49/9$

$= 15/9+49/9$

$= 64/9$

$= (8^2)/(3^2)$

Hence $x + 7/3 = +-8/3$

Subtracting 7/3 from both sides, we get

$x = +-8/3 - 7/3$

So $x = 1/3$ or $x = -15/3 = -5$ .

How do you solve 3x^2+14x=53x^2+14x=5 by completing the square?