The product of two natural numbers is 18. If one is added to four times the smaller number this is equal to the larger number. Find both numbers
2 answers
(4 * 2) +1 = 9
a = the smaller number
b = the larger number
The product of two natural numbers is 18.
This mean :
a * b = 18
If one is added to four times the smaller number this is equal to the larger number.
This mean :
1 + 4 a = b
So :
b = 1 + 4 a
Replace this value in expression :
a * b = 18
a * ( 1 + 4 a ) = 18
a + 4 a ^ 2 = 18
4 a ^ 2 + a = 18 Subtract 18 to both sides
4 a ^ 2 + a - 18 = 18 - 18
4 a ^ 2 + a - 18 = 0
The solutions are : a = - 9 / 4 and a = 2
- 9 / 4 isn't the natural number.
Solution: a = 2
b = 1 + 4 a = 1 + 4 * 2 = 1 + 8 = 9
The smaller number = 2
The larger number = 9
b = the larger number
The product of two natural numbers is 18.
This mean :
a * b = 18
If one is added to four times the smaller number this is equal to the larger number.
This mean :
1 + 4 a = b
So :
b = 1 + 4 a
Replace this value in expression :
a * b = 18
a * ( 1 + 4 a ) = 18
a + 4 a ^ 2 = 18
4 a ^ 2 + a = 18 Subtract 18 to both sides
4 a ^ 2 + a - 18 = 18 - 18
4 a ^ 2 + a - 18 = 0
The solutions are : a = - 9 / 4 and a = 2
- 9 / 4 isn't the natural number.
Solution: a = 2
b = 1 + 4 a = 1 + 4 * 2 = 1 + 8 = 9
The smaller number = 2
The larger number = 9