Answer:
(-4,-1) is the answer to this.
We have
x² + 24x = 17 (1)
Note that
(x + 12)² = x² + 24x + 144
By adding 144 to the left side of equation (1), it becomes a perfect square.
Therefore
x² + 24x = (x+12)² - 144 (2)
Substitute (2) into (1).
(x + 12)² - 144 = 17
(x + 12)² = 17 +144
(x + 12)² = 161
Answer:
We added 144 to the left side of equation (1) in order to make it a perfect square.
Answer:
140 mile
Step-by-step explanation:

While x is the speed of the second train.
Answer:
18
Step-by-step explanation:
Honestly you can just use a calculator for this.
But if you want to know how to actually do it, multiplying something by a fraction is just dividing it by its reciprocal (just flipping the numerator and the denominator).
Therefore...
72/4 is 18, 72 x 1/4 = 18
5/6, its 10/12, so just divide by two to simplify.