Try breaking these into sections.
Twice: 2 times
The sum of: add
A number: choose a variable, like x
---Thus "the sum of a number and 4" becomes "add x and 4" which, mathematically, is "x+4"
-----Continuing to put it all together, "Twice the sum of a number and four" becomes "2 times (x+4)" which, mathematically, is "2(x+4)"
Is: equals
-------"Twice the sum of a number and four is" becomes "2(x+4)="
23 less than: subtract 23. This one tends to trick people; "23 less than" will become "__ - 23", NOT "23 - __"
three times the number: 3 times x
---"23 less than three times the number" becomes "subtract 23 from 3 times x" which, mathematically, is "3x-23"
-------So the final phrase: 2(x+4)=3x-23"
5% of $55 is $2.75 so the total should be $57.75??
I'm assuming your function is f(x) = -9^(x+1)
So we just have to plug in and see if the function is true.
1) -9^(0+1) = -9^1 = -9
YES
2) -9^(1+1) = -9^2 = -81
NO
3) -9^(-1+1) = -9^0 = -1
YES
Answer:
C
Step-by-step explanation:
Try it.
