Evaluation of Algebraic Expressions and Exercise 5.1

Evaluation of Algebraic Expressions

The process of replacing the variables by numbers in an algebraic expression is called 'substitution'. The process of getting a numerical answer by substituting numbers for each variable is called 'evaluation'.

Example: Find the value of $\frac{3}{4}{x}^2-\frac{2}{3}x+1$$\frac{3}{4} x^{2} - \frac{2}{3} x + 1$ at $x=-\frac{1}{2}$$x = -\frac{1}{2}$.

Solution: $\frac{3}{4}{x}^2-\frac{2}{3}x+1$$\frac{3}{4} x^{2} - \frac{2}{3} x + 1$

By substituting the value of $x$, we have

Example: If $p = -5$ and $q = 2$, find the value of $p^{2}q+p{q}^2+2p\cdot pq$$p^{2}q + pq^{2} + 2p \cdot pq$.

Solution: $p^{2}q+p{q}^2+2p\cdot pq$$p^{2}q + pq^{2} + 2p \cdot pq$

Example: Find the value of the expression $3.1x^{4} - 0.2x^{3}y^{2} + 0.3x^{2}y^{2} + 1.1xy^{3} - y^{4}$ at $x=1, y=-1$.