Question

The area of a circle is given by the expression 9 πx square - 12 πx + 4π.find the radius of the circle when x is equals to 4 cm

Answer 1

Step-by-step explanation:

Area=\pi x^2+6\pi x+9\pi \\=\pi (x^2+6x+9)

We know, area of a circle=\pi r^2\\

\pi r^2=\pi (x^2+6x+9)\\r^2=x^2+6x+9

On factorising RHS, we get:

r^2=(x+3)(x+3)

r^2=(x+3)^2\\r=x+3

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