You need to know that a 9 grade student should perform simplifications in algebraic expressions such that: collecting like terms, expanding brackets, using distributive property in multiplication of expressions, solving one step to multi-step one variable equations, solving multi-variable equations for one variable.
Hence, you should remember when you try to solve an algebraic expression that all those letters within represent or model something.
For instance, you should know to simplify the next following algebraic expressions:
`-3x + 11 + 5x + ` 1
Simplification means to collect like terms and to write the simplified form of this expression such that:
`(-3x + 5x) + (11 + 1) = 2x + 12`
You should know to use the exponential rules to reduce numerators and denominator if needed such that:
`(xy^2)/(x^3y) = x^(1-3)*y^(2-1) = x^(-2)*y = y/(x^2)`
You should know to solve for x linear equations such that:
`5x - 7 = 3x + 3 =gt 5x - 3x = 7 + 3 =gt 2x = 10 =gt x = 10/2 =gt x = 5`
You should know to solve quadratics such that:
`4x^2 - 16 = 0 =gt 4x^2 = 16 =gt x^2 = 16/4 =gt x^2 = 4 `
`x_(1,2) = +- 2`
Hence, at a basic level, you should perform all described above considering algebraic expressions.
When asked to evaluate an algebraic expression, you are usually given values for the variables. All you have to do is plug in the values in the expression. You need to be careful though, when you have expressions containning exponents or parenthesis and some of the values are negatives.