Subtract 30, then factor the equation.
... x² = 30
... x² - 30 = 0
... (x -√30)(x +√30) = 0
By the zero product rule, the solutions are values of x that make a factor be zero.
... x - √30 = 0 . . . . the first factor is zero
... x = √30
... x + √30 = 0 . . . . the second factor is zero
... x = -√30
The solutions are . . .
... x = ±√30 . . . . . matches your 3rd choice
Answer:
Varies directly uses the formula: y/x = k
22/3 = 7.33
105/x = 7.33
105/x (7.33/x) = 7.33(x/7.33)
105/7.33 = x
x = 14.32
Answer: 18.125 lbs
Explanation: The baby weighed 18.125 pounds at the end of eight months.
The baby weighed 7.25 lbs at birth. Eight months later, he weighed 2.5 or 2½ times its birth weight. Multiply 7.25 by 2.5 (which equals 18.125).
So now eight months later, he's 18.125 pounds.
