Evaluate
3\sqrt{2}\left(\sqrt{21}-5\right)\approx -1.77098134
Factor
3 \sqrt{2} {(\sqrt{21} - 5)} = -1.77098134
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3\sqrt{6}\sqrt{7}-5\sqrt{6}\sqrt{3}
Use the distributive property to multiply \sqrt{6} by 3\sqrt{7}-5\sqrt{3}.
3\sqrt{42}-5\sqrt{6}\sqrt{3}
To multiply \sqrt{6} and \sqrt{7}, multiply the numbers under the square root.
3\sqrt{42}-5\sqrt{3}\sqrt{2}\sqrt{3}
Factor 6=3\times 2. Rewrite the square root of the product \sqrt{3\times 2} as the product of square roots \sqrt{3}\sqrt{2}.
3\sqrt{42}-5\times 3\sqrt{2}
Multiply \sqrt{3} and \sqrt{3} to get 3.
3\sqrt{42}-15\sqrt{2}
Multiply -5 and 3 to get -15.
Examples
Quadratic equation
{ x } ^ { 2 } - 4 x - 5 = 0
Trigonometry
4 \sin \theta \cos \theta = 2 \sin \theta
Linear equation
y = 3x + 4
Arithmetic
699 * 533
Matrix
\left[ \begin{array} { l l } { 2 } & { 3 } \\ { 5 } & { 4 } \end{array} \right] \left[ \begin{array} { l l l } { 2 } & { 0 } & { 3 } \\ { -1 } & { 1 } & { 5 } \end{array} \right]
Simultaneous equation
\left. \begin{cases} { 8x+2y = 46 } \\ { 7x+3y = 47 } \end{cases} \right.
Differentiation
\frac { d } { d x } \frac { ( 3 x ^ { 2 } - 2 ) } { ( x - 5 ) }
Integration
\int _ { 0 } ^ { 1 } x e ^ { - x ^ { 2 } } d x
Limits
\lim _{x \rightarrow-3} \frac{x^{2}-9}{x^{2}+2 x-3}