The sum of a number and three times another number is 18. Find the number if their product is a maximum.
x + 3y = 18
z = xy = (18-3y)(y) = 18y-3y^2
This is just a parabola with vertex (maximum value) at y=3
so, x=9, y=3
thirty times a number less three
the difference between eight and thrice a number plus eight
five less than a number is fifty
half a number decreased by ten
if the number is tripled,the result will be the same as when 28 is added to the number.What is the number
thirty times a number less three
30n-3
the difference between eight and thrice a number plus eight
8-3n+18
five less than a number is fifty
5-n=15
half a number decreased by ten
1/2n-10
if the number is tripled,the result will be the same as when 28 is added to the number.What is the number?
Answer
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Let the number be x
According to question.
3x = x+28
2x = 28
x = 14.
The number is 14.