find the value y^3-z^3 when y-z=4 and yz=-5
Answers
Answered by
2
Step-by-step explanation:
y-z=4
y=4+z
yz=-5
(4+z)z=-5
4z+z^2=-5
z^2+4z+5=0
z^2+5z-z-5=0
z(z+5)-1(z+5)=0
(z-1)(z+5)=0
Either z=1 or z=-5
y-1=4
y=5
y^3-z^3
5^3-1^3
125-1=124
Similar questions