Knowledge Check 1

1. Choose the correct option.

(a) The exponential form for [tex]$a \times a \times a \times a \times c \times c \times b \times b \times b$[/tex] is:
(i) [tex]$a^2 b^3 c^4$[/tex]
(ii) [tex][tex]$a^3 b^2 c^4$[/tex][/tex]
(iii) [tex]$a^4 b^3 c^2$[/tex]

(b) The value of [tex]$(-5)^3$[/tex] is:
(i) -125
(ii) -625
(iii) 125

(c) The power notation for [tex]$\frac{1}{10000}$[/tex] is:
(i) [tex][tex]$10^5$[/tex][/tex]
(ii) [tex]$10^4$[/tex]
(iii) [tex]$10^{-4}$[/tex]

(d) Find the value of [tex][tex]$x$[/tex][/tex] for [tex]$5^x \times 5^2 = 5^{x+2}$[/tex]:
(i) 0
(ii) 1
(iii) 2



Answer :

Sure, let's go through each part of the question step-by-step.

### Part (a) Exponential Form

To find the exponential form of the product [tex]\(a \times a \times a \times a \times c \times c \times b \times b \times b\)[/tex]:

- Count the occurrences of each variable:
- [tex]\(a\)[/tex] is multiplied 4 times.
- [tex]\(c\)[/tex] is multiplied 2 times.
- [tex]\(b\)[/tex] is multiplied 3 times.

So, the exponential form is [tex]\(a^4 b^3 c^2\)[/tex].

The correct option is:
(iii) [tex]\(a^4 b^3 c^2\)[/tex]

### Part (b) Value of [tex]\((-5)^3\)[/tex]

Calculate [tex]\((-5)^3\)[/tex]:

[tex]\[ (-5) \times (-5) \times (-5) = -125 \][/tex]

The correct option is:
(i) -125

### Part (c) Power Notation for [tex]\(\frac{1}{10000}\)[/tex]

We need to express [tex]\(\frac{1}{10000}\)[/tex] in power notation. Notice that:

[tex]\[ 10000 = 10^4 \][/tex]

So,

[tex]\[ \frac{1}{10000} = 10^{-4} \][/tex]

The correct option is:
(iii) [tex]\(10^{-4}\)[/tex]

### Part (d) Solve for [tex]\(x\)[/tex] in [tex]\(5^x \times 5^2 = 5^{x+2}\)[/tex]

Using the properties of exponents, we have:

[tex]\[ 5^x \times 5^2 = 5^{x+2} \][/tex]

For the equation to hold, the exponents must be equal:

[tex]\[ 5^{x+2} = 5^{x+2} \][/tex]

So, we see that [tex]\(x = 1\)[/tex] satisfies the equation.

The correct option is:
(ii) 1

### Summary of Correct Options

1.
(a) (iii) [tex]\(a^4 b^3 c^2\)[/tex]
(b) (i) -125
(c) (iii) [tex]\(10^{-4}\)[/tex]
(d) (ii) 1