Basic arithmetic concepts

A 1:

Which of the following statement is (are) true?

       I.            -2¹⁰>0

    II.            –(-2)¹⁰>0

 III.            2¹⁰-(-2)¹⁰>0

a)    None

b)   | only

c)    ||| only

d)   | and ||| only

e)    All are correct

Answer:

Since 2¹⁰ is positive, -2¹⁰ is negative. (| is false)

Since (-2)¹⁰ is positive, - (-2)¹⁰ is negative. (|| is false)

Since (-2)¹⁰=2¹⁰, 2¹⁰- (-2)¹⁰=0. (||| is false)

Choice a is correct.

A 2:

What is the circumference of a circle whose area is 10 π ?

a)    5π

b)   10π

c)    2π (10)^1/2

d)   π (20)^1/2

Answer:

Since the area of the circle is given by the formula A=πr², then

πr²=10π ⇒ r²=10⇒ r=  (10)^1/2

As  C=2πr, so C=2π (10)^1/2

A 3:

If a=3(x-7) and b=3x-7, what is the value of a-b?

a)    -28

b)   -14

c)    0

d)   3x-14

e)    3x+7

Answer:

a-b=3(x-7)-(3x-7)=3x-21-3x+7=-21+7=-14 (b)