Answer:
7 minutes
Step-by-step explanation:
From the question :
Descent = ascent
Initial height * descent rate = initial position * ascent rate
Plane on ground is at an initial position or height of 0
42000 - 3300t = 0 + 2700t
Where, t = time
-3300t - 2700t = 0 - 42000
-6000t = - 42000
t = 42000 / 6000
t = 7 minutes
X − 4y = 7
5x + 9y = 6
5x − 20y = 35 //1st * 5
5x + 9y = 6
5x +9y - 5x + 20y = 6 - 35 //2nd - 1st
5x + 9y = 6
29y=-29
5x=6-9y
y=-1 //1st : 29
5x=6-9*(-1)
y=-1
x=15:5 //2nd : 5
y=-1
x=3
check:
for x=3 and y=-1 there is:
x − 4y = 7 is 3 − 4*(-1) = 7 is 7=7 ok
5x + 9y = 6 is 15-9=6 is 6=6 ok
answer: (3;-1) represents the solution.
1. - 3, +4 2. +2, - 5 3. +9, +1
18y⁸z²=18y⁸z², you have to simplify it and add like terms to get your answer