jika 4-x / x+2= x, berapakah nilai dari xkuadrat +3x + 1 .....

(4 - x)/(x + 2) = x
4 - x = x(x + 2)
4 - x = x^2 + 2x
x^2 + 2x = 4 - x
x^2 + 3x = 4
Jadi
x^2 + 3x + 1 = 4 + 1 = 5