Evaluate
\frac{\left(a-2b\right)\left(2a+9b\right)}{2}
Expand
\frac{5ab}{2}+a^{2}-9b^{2}
Share
Copied to clipboard
\left(3a-6b\right)\left(\frac{1}{3}a+\frac{3}{2}b\right)
Use the distributive property to multiply 3 by a-2b.
3a\times \frac{1}{3}a+3a\times \frac{3}{2}b-6b\times \frac{1}{3}a-6b\times \frac{3}{2}b
Apply the distributive property by multiplying each term of 3a-6b by each term of \frac{1}{3}a+\frac{3}{2}b.
3a^{2}\times \frac{1}{3}+3a\times \frac{3}{2}b-6b\times \frac{1}{3}a-6b\times \frac{3}{2}b
Multiply a and a to get a^{2}.
3a^{2}\times \frac{1}{3}+3a\times \frac{3}{2}b-6b\times \frac{1}{3}a-6b^{2}\times \frac{3}{2}
Multiply b and b to get b^{2}.
a^{2}+3a\times \frac{3}{2}b-6b\times \frac{1}{3}a-6b^{2}\times \frac{3}{2}
Cancel out 3 and 3.
a^{2}+\frac{3\times 3}{2}ab-6b\times \frac{1}{3}a-6b^{2}\times \frac{3}{2}
Express 3\times \frac{3}{2} as a single fraction.
a^{2}+\frac{9}{2}ab-6b\times \frac{1}{3}a-6b^{2}\times \frac{3}{2}
Multiply 3 and 3 to get 9.
a^{2}+\frac{9}{2}ab+\frac{-6}{3}ba-6b^{2}\times \frac{3}{2}
Multiply -6 and \frac{1}{3} to get \frac{-6}{3}.
a^{2}+\frac{9}{2}ab-2ba-6b^{2}\times \frac{3}{2}
Divide -6 by 3 to get -2.
a^{2}+\frac{5}{2}ab-6b^{2}\times \frac{3}{2}
Combine \frac{9}{2}ab and -2ba to get \frac{5}{2}ab.
a^{2}+\frac{5}{2}ab+\frac{-6\times 3}{2}b^{2}
Express -6\times \frac{3}{2} as a single fraction.
a^{2}+\frac{5}{2}ab+\frac{-18}{2}b^{2}
Multiply -6 and 3 to get -18.
a^{2}+\frac{5}{2}ab-9b^{2}
Divide -18 by 2 to get -9.
\left(3a-6b\right)\left(\frac{1}{3}a+\frac{3}{2}b\right)
Use the distributive property to multiply 3 by a-2b.
3a\times \frac{1}{3}a+3a\times \frac{3}{2}b-6b\times \frac{1}{3}a-6b\times \frac{3}{2}b
Apply the distributive property by multiplying each term of 3a-6b by each term of \frac{1}{3}a+\frac{3}{2}b.
3a^{2}\times \frac{1}{3}+3a\times \frac{3}{2}b-6b\times \frac{1}{3}a-6b\times \frac{3}{2}b
Multiply a and a to get a^{2}.
3a^{2}\times \frac{1}{3}+3a\times \frac{3}{2}b-6b\times \frac{1}{3}a-6b^{2}\times \frac{3}{2}
Multiply b and b to get b^{2}.
a^{2}+3a\times \frac{3}{2}b-6b\times \frac{1}{3}a-6b^{2}\times \frac{3}{2}
Cancel out 3 and 3.
a^{2}+\frac{3\times 3}{2}ab-6b\times \frac{1}{3}a-6b^{2}\times \frac{3}{2}
Express 3\times \frac{3}{2} as a single fraction.
a^{2}+\frac{9}{2}ab-6b\times \frac{1}{3}a-6b^{2}\times \frac{3}{2}
Multiply 3 and 3 to get 9.
a^{2}+\frac{9}{2}ab+\frac{-6}{3}ba-6b^{2}\times \frac{3}{2}
Multiply -6 and \frac{1}{3} to get \frac{-6}{3}.
a^{2}+\frac{9}{2}ab-2ba-6b^{2}\times \frac{3}{2}
Divide -6 by 3 to get -2.
a^{2}+\frac{5}{2}ab-6b^{2}\times \frac{3}{2}
Combine \frac{9}{2}ab and -2ba to get \frac{5}{2}ab.
a^{2}+\frac{5}{2}ab+\frac{-6\times 3}{2}b^{2}
Express -6\times \frac{3}{2} as a single fraction.
a^{2}+\frac{5}{2}ab+\frac{-18}{2}b^{2}
Multiply -6 and 3 to get -18.
a^{2}+\frac{5}{2}ab-9b^{2}
Divide -18 by 2 to get -9.
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}