Equations can contain more than one variable. For example, the following equation has two variables, and
To solve the equation for the variable we need to isolate on one side of the equation:
In this case, we apply the addition principle and add to both sides:
And that's it! We have successfully isolated the variable
Let's now look at an example where we must apply the multiplication principle.
Solve the equation for the variable
We need to isolate the variable To do this, we treat as though it were a constant and apply the addition and multiplication principles as usual.
In this case, we simply divide both sides of the equation by
If $h-\dfrac{3}{2}k=2$ then $h=$
|
a
|
$2+\dfrac{3}{2}k$ |
|
b
|
$2+3k$ |
|
c
|
$2+2k$ |
|
d
|
$2-\dfrac{3}{2}k$ |
|
e
|
$\dfrac{3}{2}k$ |
If $x+k=5,$ then $x=$
|
a
|
$5+k$ |
|
b
|
$k-5$ |
|
c
|
$5-k$ |
|
d
|
$\dfrac{5}{k}$ |
|
e
|
$-5k$ |
If $\dfrac{x}{5}=y,$ then $x=$
|
a
|
$y-5$ |
|
b
|
$5y$ |
|
c
|
$y+5$ |
|
d
|
$\dfrac 5y$ |
|
e
|
$\dfrac y5$ |
Given that express in terms of
We need to isolate the variable To do this, we treat as though it were a constant and apply the addition and multiplication principles as usual.
First, we subtract from both sides of the equation:
Then, we multiply both sides of the equation by
If $3x-4y=5y$ then $x=$
|
a
|
$3y$ |
|
b
|
$3x$ |
|
c
|
$\dfrac{y}{3}$ |
|
d
|
$-3y$ |
|
e
|
$-\dfrac{y}{3}$ |
If $\dfrac{s}{4}+\dfrac{t}{2}=1$ then $s=$
|
a
|
$4 + 2t$ |
|
b
|
$4 + \dfrac{t}{2} $ |
|
c
|
$2 - \dfrac{t}{2} $ |
|
d
|
$1 - \dfrac{t}{2} $ |
|
e
|
$4 - 2t$ |
If $3a + b = 12a,$ then $a = $
|
a
|
$\dfrac b {15}$ |
|
b
|
$15b$ |
|
c
|
$\dfrac b 9$ |
|
d
|
$9b$ |
|
e
|
$\dfrac 9 b$ |
Solve the following equation for the variable
We need to isolate the variable First, we cross-multiply:
Next, we add to both sides of the equation:
Finally, we divide both sides of the equation by
If $4m - 6n = 3n - 7$, then $n=$
|
a
|
$\dfrac{m + 7}{9}$ |
|
b
|
$\dfrac{4m + 7}{9}$ |
|
c
|
$\dfrac{4m - 7}{9}$ |
|
d
|
$\dfrac{2m + 7}{9}$ |
|
e
|
$\dfrac{2m - 7}{9}$ |
If $\dfrac{4x-3y}{2}=\dfrac{1-y}{3},$ then $x=$
|
a
|
$- \dfrac{2x+7}{12y}$ |
|
b
|
$\dfrac{2 +7y}{12}$ |
|
c
|
$\dfrac{7}{12}$ |
|
d
|
$\dfrac{7 -2y}{4}$ |
|
e
|
$\dfrac{7y}{3}$ |
If $\dfrac{f - 2}{5} = \dfrac{5g - 2f}{6},$ then $f=$
|
a
|
$ \dfrac{g + 12}{5}$ |
|
b
|
$ \dfrac{21g + 12}{12}$ |
|
c
|
$ \dfrac{23g - 12}{10}$ |
|
d
|
$ \dfrac{25g + 12}{16}$ |
|
e
|
$ \dfrac{24g + 2}{6}$ |