What are the solutions to the equation 81pi=pi*r^2 ?

The solutions to the equation 81pi=pi*r^2 are r=-9,r=9

Find the zeros of 81pi=pi*r^2

The zeros of 81pi=pi*r^2 are r=-9,r=9

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81 π = π \cdot r^{2}

r = - 9, r = 9

Solution steps

81 π = π r^{2}

Move

π \cdot r^{2}

to the left side

81 π - π r^{2} = 0

Factor

81 π - π r^{2} : - π (r + 9) (r - 9)

- π (r + 9) (r - 9) = 0

Using the Zero Factor Principle:

ab = 0

then

a = 0

b = 0

r + 9 = 0 or r - 9 = 0

Solve

r + 9 = 0 : r = - 9

Solve

r - 9 = 0 : r = 9

The solutions to the quadratic equation are:

r = - 9, r = 9

y^{2} = 13

x^{2} - 3 x + 5 = 0

x^{2} = \frac{x - 3}{2}

x^{2} + 72 = - 18 x

9 x^{2} - 15 x + 36 = 0

What are the solutions to the equation 81pi=pi*r^2 ?
The solutions to the equation 81pi=pi*r^2 are r=-9,r=9
Find the zeros of 81pi=pi*r^2
The zeros of 81pi=pi*r^2 are r=-9,r=9