a) x2 + 18x - 1600 = 0
=> x2 + 50x - 32x - 1600 = 0
=> x(x + 50) - 32(x + 50) = 0
=> (x + 50)(x - 32) = 0
=> x = -50; x = 32
b) x2 + 32x - 900 = 0
=> x2 + 50x - 18x - 900 = 0
=> x(x + 50) - 18(x + 50) = 0
=> (x + 50)(x - 18) = 0
=> x = -50; x = 18
c) x2 + 27x - 3600 = 0
=> x2 + 75x - 48x - 3600 = 0
=> x(x + 75) - 48(x + 75) = 0
=> (x + 75)(x - 48) = 0
=> x = -75; x = 48
d) x2 + 48x - 2025 = 0
=> x2 + 75x - 27x - 2025 = 0
=> x(x + 75) - 27(x + 75) = 0
=> (x + 75)(x - 27) = 0
=> x = -75; x = 27
x2 + 18x -1600 = 0
(a=1, b= 18, c=-1600)
=>b'=9
\(\Delta'=9^2-1.\left(-1600\right)=1681\)
Vì Δ'>0 nên PT có 2 nghiệm phân biệt
\(x_1=\frac{-9+\sqrt{1681}}{1}=32\)
\(x_1=\frac{-9-\sqrt{1681}}{1}=-50\)
Vây PT có 2 nghiệm x1=32 ; x2=-50
x2 + 32x -900 = 0
(a=1, b= 32, c=-900)
=>b'=16
\(\Delta'=16^2-1.\left(-900\right)=1156\)
Vì Δ'>0 nên PT có 2 nghiệm phân biệt
\(x_1=\frac{-16+\sqrt{1156}}{1}=18\)
\(x_2=\frac{-16-\sqrt{1156}}{1}=-50\)
Vậy.......
