Chapter 9

If b2=a then b is the square root of a. All positive real numbers have two square roots: a

positive square root and a negative square root. Square roots are written with a radical symbol√, the

number inside the symbol is the radicand. Numbers whose square roots are whole numbers are

called perfect squares. The square roots of numbers that are not perfect

squares are part of the set of irrational numbers. A radical expression involves square roots (or

radicals). A quadratic equation is an equation where the highest

power of the variable is 2. The standard form of a quadratic equation is

ax2 + bx + c=0.

Entry Task, write this down

A quadratic equation of the form ax2 + bx + c=0 can be solved using the quadratic formula.

This formula can also be used to find where the function f(x)= ax2 + bx + c crosses the x axis

Entry Task: copy this downThe quadratic Formula

Quadratic Functions

F(x) = ax2 + bx + c

a

acbbx

2

42

a

bx

2