Solve sqrt{21^2-4(-28)27}

$$\sqrt { 21 ^ { 2 } - 4 ( - 28 ) 27 }$$

Evaluate

$$3\sqrt{385}\approx 58.864250611$$

Solution Steps

Calculate 21 to the power of 2 and get 441.

$$\sqrt{441-4\left(-28\right)\times 27}$$

Multiply 4 and -28 to get -112.

$$\sqrt{441-\left(-112\times 27\right)}$$

Multiply -112 and 27 to get -3024.

$$\sqrt{441-\left(-3024\right)}$$

The opposite of -3024 is 3024.

$$\sqrt{441+3024}$$

Add 441 and 3024 to get 3465.

$$\sqrt{3465}$$

Factor 3465=3^{2}\times 385. Rewrite the square root of the product \sqrt{3^{2}\times 385} as the product of square roots \sqrt{3^{2}}\sqrt{385}. Take the square root of 3^{2}.

$$3\sqrt{385}$$