Answer:
-8 + x ≥ 9
Step-by-step explanation:
Let's look at your sentence:
The <u>sum of -8 and a number</u> is <u>at least 9 </u>what is the equation look like
Sum is the result of adding
At least 9 means that the number is 9 or greater.
So what you have here is an inequality expression:
Sum of -8 and a number
-8 + x
x here is the "number" since we do not know the value we will use "x" to represent that number.
At least 9
At least means that it is equal or greater, so we use this expression ≥
and so we use put that all together
-8 + x ≥ 9
Answer:
6.32 years
Step-by-step explanation:
To get the time taken to triple the amount invested, we must first establish the compound interest formula. When a principal amount P is invested for a time n at a rate r percent, the amount A after n years may be expressed as
A = P (1 + r)^n
Hence if $1,225 is to triple, the amount will be
= $1,225 *3
= $3,675
The time n for this to happen may be computed through the equation
$3,675 = $1,225 ( 1 + 0.19)^n
3 = 1.19^n
take the log of both sides
log 3 = log 1.19^n
using the law of logarithms that log a^b = b log a
n log 1.19 = log 3
n = log 3 / log 1.19
n = 6.32 years
