College test english 8 pps

LearningExpress Skill Builders • CHAPTER 4 79

If the answer is zero, then we know that one of those

quantities (one of those somethings) has to be zero. So

we set both of those somethings equal to 0.

(x 2)(x  8)  0

x 2  0 | x  8  0

x  2 | x  8

Thus, the answer is b.

2. If x is a positive number, and x2 8x  9  0,

what is the value of x?

a. 1

b. 9

c. all of the above

d. none of the above

The expression x2 8x  9  0 can be factored into

two sets of parentheses:

(x ± ?)(x ± ?)  0

Again, because the coefficient of the x2 term is 1, we

know that the sum of the two missing numbers is 8

(the coefficient of the x term) and the product of the

two missing numbers is 9 (the lone number). The two

numbers that satisfy these conditions are 9 and 1. We

fill in our parentheses and set each set of parentheses

equal to 0:

(x 9)(x  1)  0

x 9  0 | x  1  0

x  9 | x  1

But be careful! The question told us that x is positive!

This means that only 9 is correct, choice b.

SKILL BUILDER QUESTIONS

1. John has a box containing 84 nails, and he finds

47 around his workshop. If his current project

requires four times the amount he already has,

how many more nails does he have to buy?

a. 131

b. 524

c. 393

d. 84

2. How much is one-eighth of one-sixth?

a. 4

1

8

b.

6

8

c. 1

1

2

d.

1

6

3. For every dollar Zelda saves, her dad contributes

a dime to her savings. If Zelda saves $10 in June,

$25 in July and $13 in August, how much will

she have in savings at the end of that time?

a. $52.80

b. $52.00

c. $53.80

d. $48.00

4. Jessica is having a party and is making a sparkling

drink. Her recipe calls for 1 part fruit punch and

2 parts Sprite. If she adds 3 cups of fruit punch,

how much Sprite would she need?

a. 2 cups

b. 6 cups

c. 3 cups

d. 4 cups

5. Change 42% to a fraction.

a. 4

1

2

b. 4

1

.2

c.

2

5

1

0

d. 1

4

0

.2

0

–ESSENTIAL PRACTICE WITH MATH–