Question

Решите уравнение (5-2х)^2 - 9(х+1)^2=0

Answer 1

(5-2x)²-9(x+1)²=0
25-20x+4x²-9(x²+2x+1)=0
25-20x+4x²-9x²-18x-9=0
-5x²-38x+16=0
5x²+38x-16=0
D=38²-4.5.(-16)=1444+320=1764,√D=√1764=42
x1=(-38+42)/10=4/10=2/5=0,4
x2=(-38-42)/10=-80/10=-8