Answer:
see explanation
Step-by-step explanation:
given x² - 6x - 21 = 0 ( add 21 to both sides )
x² - 6x = 21
to complete the square
• add ( half the coefficient of the x-term)² to both sides
x² + 2 (- 3)x +9 = 21 + 9
(x - 3)² = 30 ( take the square root of both sides )
x - 3 = ±
( add 3 to both sides )
x = 3 ± 
x = 3 -
= - 2.48 ( to 2 dec. places ) or
x = 3 +
= 8.48 ( to 2 dec. places )
Odd integers are 2 apart
the 3 consecutive odd numbers are x,x+2, x+4
sum is x+x+2+x+4 or 3x+6
the sum is 15 more than 2 times middle one
3x+6=15+2(x+2)
3x+6=15+2x+4
3x+6=19+2x
minus 2x both side
x+6=19
minus 6 both sides
x=13
x+2=15
x+4=17
they are 13,15,17
Well the teacher would only get $15 but we don’t know how much the balls cost so you can’t make an expression