Solve for x
x = -\frac{21}{2} = -10\frac{1}{2} = -10.5
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3x-21-6x=-x
Use the distributive property to multiply 3 by x-7.
-3x-21=-x
Combine 3x and -6x to get -3x.
-3x-21+x=0
Add x to both sides.
-2x-21=0
Combine -3x and x to get -2x.
-2x=21
Add 21 to both sides. Anything plus zero gives itself.
x=\frac{21}{-2}
Divide both sides by -2.
x=-\frac{21}{2}
Fraction \frac{21}{-2} can be rewritten as -\frac{21}{2} by extracting the negative sign.
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}