Easy Mathematics for Biologists by Peter C.Foster

Author:Peter C.Foster
Format: mobi, pdf
Publisher: PageMaker 6.5
Published: 2003-10-19T16:00:00+00:00

means’ the square root of what is under the sign’.

A square root of a number is one of its equal factors.

=the number a such that a2=b

* * *

Solving Equations and Evaluating Expressions

43

It is not essential that you know how this formula is derived. However, you

should be aware of its existence and be able to use it.

Example 5.11

Note these are the same solutions as you would get by factoring.

5.2 EVALUATING EXPRESSIONS

To evaluate an expression, substitute the given values for the unknown variable.

You should already be familiar with this for simple examples.

Example 5.12

The circumference c of a circle is given by the formula

c=πd where d is the diameter. What is the circumference of a circle

with a diameter of 5 m?

c=π(5)=15.7 m

Example 5.13

What is the radius of a circle with a circumference of 15.7 m?

c=πd rearranges to d=c/π

d=15.7/π=5

radius=d/2=5/2=2.5 m

Example 5.14

What is the area A of a circle of radius 3 m if the area is given by

the formula A=πr2 where r is the radius?

A=π(3)2=28.3 m2

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