|
Example 1
What is the value of $(-x^3 + y^2)-2( - x^2 - y^3 )$ for $x = - 2$ and $y = - 3$ ?
- $9$
- $-9$
- $-29$
- $29$
- $-30$
Solution
This example is about substitution in and evaluation of algebraic expressions.
- According to the $5$ possible answers, we need to evaluate the given expression by substituting $x$ by $\color{red}{(-2)}$ and $y$ by $\color{blue}{(-3)}$ in the given algebraic expression as follows:(NOTE the use of parentheses)
$(-x^3 + y^2)-2( - x^2 - y^3 )= (-\color{red}{(-2)}^3 +\color{blue}{(-3)}^2)-2( - \color{red}{(-2)}^2 - \color{blue}{(-3)}^3 )$
- Simplify (you may use the calculator at this point)
$=(-(-8) +9)-2( - 4 - (-27) )$
$=(8+9)-2(-4+27)$
$=17-2(23)$
$=17-46$
$=-29$
Answer C
|