Answer:
2pi(3x + 7)
Step-by-step explanation:
In order to solve for the circumference, consider the area and circumference formulas. What is common among them? The radius. Take a look at their formulas below;
[tex]Circumference = 2\pi r,\\Area = \pi r^2,\\\\Where, r = radius[/tex]
Now if the area of this circle is given to be π ( 9x^2 + 42x + 49 ) we can plug it into the area formula as " Area " and solve for r ( radius );
[tex]\pi * ( 9x^2 + 42x + 49 ) = \pi r^2,\\( 9x^2 + 42x + 49 ) = r^2[/tex]
As you can see, π was eliminated on either side of the equation, leaving us with the simplified equation ( 9x^2 + 42x + 49 ). This expression is a perfect square. How so? Well you can rewrite the expression as ( 3x )^2 + 2 * ( 3x ) * ( 7 ) + ( 7 )^2, or ( 3x + 7 )^2;
[tex]( 3x + 7 )^2 = r^2,\\r = | 3x + 7 |,\\r = 3x + 7, r = - 3x - 7\\\\Solution, r = 3x + 7[/tex]
If r = 3x + 7, let us plug it into the circumference formula as to solve for the circumference;
[tex]Circumference = 2\pi r,\\Circumference = 2\pi * ( 3x + 7 )[/tex]
Solution = 2pi(3x + 7)
