Solve r^2=1256/4*3.14

$$r ^ { 2 } = \frac { 1256 } { 4 \times 3.14 }$$

Solve for r

$$r=10$$

$$r=-10$$

Steps Using Difference of Squares

Multiply 4 and 3.14 to get 12.56.

$$r^{2}=\frac{1256}{12.56}$$

Expand \frac{1256}{12.56} by multiplying both numerator and the denominator by 100.

$$r^{2}=\frac{125600}{1256}$$

Divide 125600 by 1256 to get 100.

$$r^{2}=100$$

Subtract 100 from both sides.

$$r^{2}-100=0$$

Consider r^{2}-100. Rewrite r^{2}-100 as r^{2}-10^{2}. The difference of squares can be factored using the rule: a^{2}-b^{2}=\left(a-b\right)\left(a+b\right).

$$\left(r-10\right)\left(r+10\right)=0$$

To find equation solutions, solve r-10=0 and r+10=0.

$$r=10 r=-10$$

Steps by Finding Square Root

Multiply 4 and 3.14 to get 12.56.

$$r^{2}=\frac{1256}{12.56}$$

Expand \frac{1256}{12.56} by multiplying both numerator and the denominator by 100.

$$r^{2}=\frac{125600}{1256}$$

Divide 125600 by 1256 to get 100.

$$r^{2}=100$$

Take the square root of both sides of the equation.

$$r=10 r=-10$$

Steps Using the Quadratic Formula

Multiply 4 and 3.14 to get 12.56.

$$r^{2}=\frac{1256}{12.56}$$

Expand \frac{1256}{12.56} by multiplying both numerator and the denominator by 100.

$$r^{2}=\frac{125600}{1256}$$

Divide 125600 by 1256 to get 100.

$$r^{2}=100$$

Subtract 100 from both sides.

$$r^{2}-100=0$$

This equation is in standard form: ax^{2}+bx+c=0. Substitute 1 for a, 0 for b, and -100 for c in the quadratic formula, \frac{-b±\sqrt{b^{2}-4ac}}{2a}.

$$r=\frac{0±\sqrt{0^{2}-4\left(-100\right)}}{2}$$

Square 0.

$$r=\frac{0±\sqrt{-4\left(-100\right)}}{2}$$

Multiply -4 times -100.

$$r=\frac{0±\sqrt{400}}{2}$$

Take the square root of 400.

$$r=\frac{0±20}{2}$$

Now solve the equation r=\frac{0±20}{2} when ± is plus. Divide 20 by 2.

$$r=10$$

Now solve the equation r=\frac{0±20}{2} when ± is minus. Divide -20 by 2.

$$r=-10$$

The equation is now solved.

$$r=10 r=-10$$