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Example 1
Evaluate $x^2-2x+1$
for $x=-2$
Solution
- Substitute $x$ included in the expression $x^2-2x+1$ by $(-2)$ as follows
${\color{red}{(-2)}}^2-2{\color{red}{(-2)}}+1$
- Simplify
(YOU MAY USE A CALCULATOR)
$=4-4+1$
$=1$
Example 2
If $x=-1$ and $y = 2$, then $2xy+x^2-y^2 = $
Solution
- Substitute $x$ by $(-1)$ and $y$ by ${\color{blue}{(2)}}$ in the given expression $2xy+x^2-y^2$ as follows
$2{\color{red}{(-1)}}{\color{blue}{(2)}}+{\color{red}{(-1)}}^2-{\color{blue}{(2)}}^2$
- Simplify
(YOU MAY USE A CALCULATOR)
$=-8+1-4$
$=-11$
Example 3
If $x=1$ and $y = -2$, then $\dfrac{2x+3y}{4x+7y} = $
Solution
- Substitute $x$ by $(1)$ and $y$ by ${\color{blue}{(-2)}}$ in the given expression $\dfrac{2x+3y}{4x+7y}$ as follows
$\dfrac{ 2{\color{red}{(1)}} + 3{\color{blue}{(-2)}} } { 4{\color{red}{(1)}} + 7{\color{blue}{(-2)}} }$
- Simplify
(YOU MAY USE A CALCULATOR)
$=\dfrac{2-6}{4-14}$
$=\dfrac{-4}{-10}$
$=\dfrac{2}{5}$
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