Question

Sa se rezolve ecuatiile :
c) $\sqrt{ x^{2} -16} =3$
d) $\sqrt{x ^{2}-8x }=3$
g) $\sqrt[3]{8-7x} =-3$

Answer 1

 c)  ↑² 
x²-16=3²
x²-16=9
x²=16+9
x²=25
x=√25
x₁=+5   si  x₂=-5
d)  ↑²
x²-8x=3²
x²-8x=9
x²-8x-9=0
Δ=64-4×(-9)
Δ=64+36⇒Δ=100
X₁=-b+√Δ / 2a  ⇒x₁=8+10/2=9
X₂=-b-√Δ/2a⇒X₂=8-10/2=-1
g) ↑³
8-7x=(-3)³
8-7x=-27
-7x=-27-8
-7x=-35
x=-35/(-7)= 5