Answer:
-(-5) ± √13 5 ± √13
x = ----------------------- = ---------------
2(3) 6
Step-by-step explanation:
This is a quadratic equation, with coefficients 3, -5 and 1.
The discriminant, b² - 4ac, turns out to be (-5)² - 4(3)(1), or 25 - 12 = 13
Thus, the roots are:
-(-5) ± √13 5 ± √13
x = ----------------------- = ---------------
2(3) 6
Answer: the total number of coupon books sold is 20.
Step-by-step explanation:
Let x represent the number of coupon books that Mario sold.
Let y represent the number of coupon books that Luigi sold.
Apparently, Mario is a much better salesperson, because he sold 4 times as many coupon books as Luigi. This is expressed as
x = 4y
If Luigi sold 12 fewer coupon books than Mario, the expression would be
x = y + 12 - - - - - - - - - - -- -1
Substituting x = 4y into equation 1, it becomes
4y = y + 12
4y - y = 12
3y = 12
y = 12/3
y = 4
x = 4y = 4 × 4
x = 16
The total number of coupon books that the two boys sold is
4 + 16 = 20
