Question

aca x apartine z si x plus 1 supra 5 egal 20 supra x plus 1 atunci x apatine

Answer 1

$\frac{x+1}{5}= \frac{20}{x+1}$
(x+1)²=5*20
(x+1)²=100
x²+2x+1=100
x²+2x+1-100=0
x²+2x-99=0
Δ=4-4*(-99)=4+396=400
√Δ=√400=20
x1=(-2+20)/2=18/2=9
x2=(-2-20)/2=-22/2=-11
x∈{-11;9}