Answer :
To evaluate the expression [tex]\( n^2 - 9n - 5 \)[/tex] when [tex]\( n = 4 \)[/tex], let's follow these steps:
1. Substitute [tex]\( n = 4 \)[/tex] into the expression [tex]\( n^2 - 9n - 5 \)[/tex].
So, the expression becomes [tex]\( 4^2 - 9(4) - 5 \)[/tex].
2. Calculate [tex]\( 4^2 \)[/tex]:
[tex]\( 4^2 = 16 \)[/tex].
3. Calculate [tex]\( 9 \times 4 \)[/tex]:
[tex]\( 9 \times 4 = 36 \)[/tex].
4. Substitute these values back into the expression:
The expression now is [tex]\( 16 - 36 - 5 \)[/tex].
5. Perform the subtraction in steps:
First, subtract [tex]\( 36 \)[/tex] from [tex]\( 16 \)[/tex]:
[tex]\( 16 - 36 = -20 \)[/tex].
Next, subtract [tex]\( 5 \)[/tex] from [tex]\( -20 \)[/tex]:
[tex]\( -20 - 5 = -25 \)[/tex].
Therefore, the value of the expression [tex]\( n^2 - 9n - 5 \)[/tex] when [tex]\( n = 4 \)[/tex] is [tex]\(-25\)[/tex].
1. Substitute [tex]\( n = 4 \)[/tex] into the expression [tex]\( n^2 - 9n - 5 \)[/tex].
So, the expression becomes [tex]\( 4^2 - 9(4) - 5 \)[/tex].
2. Calculate [tex]\( 4^2 \)[/tex]:
[tex]\( 4^2 = 16 \)[/tex].
3. Calculate [tex]\( 9 \times 4 \)[/tex]:
[tex]\( 9 \times 4 = 36 \)[/tex].
4. Substitute these values back into the expression:
The expression now is [tex]\( 16 - 36 - 5 \)[/tex].
5. Perform the subtraction in steps:
First, subtract [tex]\( 36 \)[/tex] from [tex]\( 16 \)[/tex]:
[tex]\( 16 - 36 = -20 \)[/tex].
Next, subtract [tex]\( 5 \)[/tex] from [tex]\( -20 \)[/tex]:
[tex]\( -20 - 5 = -25 \)[/tex].
Therefore, the value of the expression [tex]\( n^2 - 9n - 5 \)[/tex] when [tex]\( n = 4 \)[/tex] is [tex]\(-25\)[/tex].
