In this lecture, we show how algebraic operations are
used in solving equations. In the following sections, we
show some of the important applications of equations.
An equation is an algebraic statement that two algebraic
expressions are equal. Any value of the unknown that
produces equality when substituted in the equation is
said to satisfy the equation and is called a solution of
the equation.
RATIO AND PROPORTION
The quotient a/
b is also called the
ratio
of a to b. An equation stating that two
ratios are equal is called a
proportion
. Because a proportion is an equation, if one
of the numbers is unknown, we can solve for its value as with any equation. Usually,
this is done by noting the denominators and multiplying each side by a number that
will clear the fractions.
.
Quadratic equation:
ax²+bx+c=0; a,b,c € R
𝑥 =
−𝑏 ± 𝑏
2
− 4𝑎𝑐
2𝑎
If b²-4ac > 0, it has two real roots
If b²-4ac = 0, it has a unique root
If b²-4ac < 0, it does not have a real root
.
Special cases of quadratic equation
Given ax²+2bx+c=0;
𝑥 =
−𝑏± 𝑏
2
−𝑎𝑐
𝑎
Viet theorem:
x²+px+q=0;
𝑥1 + 𝑥2 = −𝑝
𝑥1 ∗ 𝑥2 = 𝑞
.
Equation
– a statement that the values of two mathematical expressions are
equal
Linear equation:
ax+b=0; a,b € R
a≠0 and b ≠0 it has a unique solution
a=0 and b=0 it has infinitely many solution
a=0 and b ≠0 it does not exist
Linear equation is a first order equation