Solve for a
a=5
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-a-\left(-7\right)=-2\left(4-a\right)
To find the opposite of a-7, find the opposite of each term.
-a+7=-2\left(4-a\right)
The opposite of -7 is 7.
-a+7=-8+2a
Use the distributive property to multiply -2 by 4-a.
-a+7-2a=-8
Subtract 2a from both sides.
-3a+7=-8
Combine -a and -2a to get -3a.
-3a=-8-7
Subtract 7 from both sides.
-3a=-15
Subtract 7 from -8 to get -15.
a=\frac{-15}{-3}
Divide both sides by -3.
a=5
Divide -15 by -3 to get 5.
Examples
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{ x } ^ { 2 } - 4 x - 5 = 0
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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}