Intermediate Algebra (11th edition)

132.The illumination I, in foot-candles, produced by a light source is related to the distance d,

in feet, from the light source by the equation

where kis a constant. If , how far from the light source will the illumination be 2 foot-

candles? Give the exact value, and then round to the nearest tenth of a foot.

Refer to the Chapter Opener on page 427.Recall that an isosceles triangleis a triangle that

has two sides of equal length.

133.The statement made by the Scarecrow in The Wizard of Ozcan be proved

false by providing at least one situation in which it leads to a false statement.

Use the isosceles triangle shown here to prove that the statement is false.

134.Use the same style of wording as the Scarecrow to state the Pythagorean

theorem correctly.

The table gives data on three different solar modules available for roofing.

k= 640

d=

B

k

I

,

SECTION 8.4 Adding and Subtracting Radical Expressions 453

4

99

Source:Solarex table in Jade Mountain catalog.

Size (in Cost (in

Model Watts Volts Amps inches) dollars)

MSX-77 77 16.9 4.56 475

MSX-83 83 17.1 4.85 490

MSX-60 60 17.1 3.5 44 * 20 382

44 * 24

44 * 26

You must determine the size of frame needed to support each panel on a roof. (Note: The sides

of each frame will form a right triangle, and the hypotenuse of the triangle will be the width of

the panel.) In Exercises 135–136, use the Pythagorean theorem to find the dimensions of the

legs for each frame under the given conditions. Round answers to the nearest tenth.

135.The legs have equal length. 136.One leg is twice the length of the other.

Combine like terms. See Section 5.2.

137. 
     
     
     
     138. 
          
     
     
     
     


138. 9 q^2 + 2 q- 5 q-q^2 140. 7 m 5 - 2 m^3 + 8 m 5 - m^3

13 x 4 - 12 x^3 + 9 x 4 + 2 x 3 - 15 z^3 - z^2 + 4 z^4 + 12 z^8

PREVIEW EXERCISES

OBJECTIVE

Adding and Subtracting Radical Expressions

8.4

1 Simplify radical
expressions
involving addition
and subtraction.

OBJECTIVE 1 Simplify radical expressions involving addition and

subtraction.Expressions such as and can be simpli-

fied using the distributive property.

= 12 - 5223 =- 323

223 - 523

= 14 + 3222 = 722

422 + 322

4  2 + 3  2 2  3 - 5  3

⎧

⎨

⎩

⎧

⎨

⎩

This is similar to

simplifying to 7x.

This is similar to

simplifying to 2 x- 5 x - 3 x.

4 x+ 3 x