Find the real zeros
x^4-40x^2+144=0

the first choice 2 ; -2 ; 6 :-6

Step-by-step explanation:

1) method : you can put this values 2 ; -2 ; 6 :-6 you are 0

2) method  you can solve this equation

x^4-40x^2+144=0

let : x² = t   and t ≥ 0

t² -40t +144 = 0

Δ = b²- 4ac    a= 1           b = - 40         c = 144

Δ =(-40)²- 4(1)(144= 1600 -576 = 1024=32²

t1 = (40+32)/2 = 36 = 6²

t1 = (40-32)/2 = 4 = 2²

but :  x² = t   and t ≥ 0

1)case    :    x² = 6²       x = 6 or x= -6

2() case : x² =2²          x = 2 or x= -2

14 ft 7 inches

step-by-step explanation:

since each model inch corresponds to 25 real inches, 7 model inches will correspond to

7×25" = 175"

at 12" per foot, that is 14 feet, 7 inches.