Question

I need help with math fast (well explained) worth 18 points!!!!!!!!!!

1: a ball is arremesada in the air and its height above the ground in time X (in seconds) is given by the function F (x) = x² - 5x. Determine how long the ball hit the ground again.

2: A banking application yields a day x Mesum value in real given by the function f (x) = x² - 4x - 5. Determine the days when there is no income that application.

Help me :)

Answer 1

1. so just subsitute numbers if we subsitute 5 for x then we get 0 if it's height is 6 then the time will be 16

2. so you want to factor the equation and get f(x)=x^2-4x-5=(x-5)(x+1) then set this equation = to 0 so (x-5)(x+1)=0
x-5 or x+1 must equal 0 so
x-5=0
x=5
x+1=0
x=-1
discard this because you cannot yield a negative ammount

so when the bank yields 5 in a day, the income is 0