Evaluate Expressions
Example corresponding about evaluating expressions
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Example 1
If $x=2\dfrac{1}{4}$ and $y=2\dfrac{2}{3}$, then $4x-6y-6=$
- $-13$
- $13$
- $31$
- $-31$
- $22$
Solution
This example is about evaluating expressions.
- We first need to understand the mixed numbers. The mixed number $2\dfrac{1}{4}$ is equivalent to ${\color{red}{2+\dfrac{1}{4}}}$ and $2\dfrac{2}{3}$ is equivalent to ${\color{blue}{2+\dfrac{2}{3}}}$. We now substitute $x$ and $y$ by the mixed numbers ${\color{red}{2+\dfrac{1}{4}}}$ and ${\color{blue}{2+\dfrac{2}{3}}}$ in the given expression.
$4x-6y-6$
$=4{\color{red}{(2+\dfrac{1}{4})}}-6{\color{blue}{(2+\dfrac{2}{3})}}-6$
- We now now expand and simplify
$= 4 \times 2 + 4 \times \dfrac{1}{4} -6 \times 2 - 6 \times \dfrac{2}{3}-6$
$= 8 + 1 - 12 - 4 - 6$
$= -13$
Answer A
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