Quadratic expressions

A quadratic expression is an expression where the highest exponent of the variable (usually $x$) is a square ($x^2$). It is usually written as $ax^2 + bx + c$.

Quadratic expression has the general form of $ax^2 + bx + c$ where $a \neq 0$ and $a$ is a coefficient of $x^2$, $b$ is a coefficient of $x$ and $c$ is a constant. Its highest power of variable is 2. Examples of quadratic expressions are $2x^2 + x + 1$, $4y^2 + 3$, $3z^2 - 4z + 1$ and so on. In a quadratic expression $3z^2 - 4z + 1$, $a = 3$, $b = -4$ and $c = 1$. Also in quadratic expression $4y^2 + 3$, $a = 4$, $b = 0$ and $c = 3$

Find the area of a rectangle with a length of $4y + 3$ and a width of $2y + 1$.

Solution

$3x$ items were bought and each item costs $(4x - 3)$ shillings. Find total amount of money used.