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You are given
2xyz + yz > 3xyz, (1)
y > 0, (2)
z < 0. (3)
Add -3xyz to both sides of inequality (1). You will get an equivalent inequality
-xyz + yz > 0.
Factor out yz in the last inequality. You will get an equivalent inequality
yz*(-x+1) > 0.
Divide both sides by yz. Since yz is NEGATIVE, do not forget to replace the inequality sign by the opposite.
You will get an equivalent inequality
-x + 1 < 0.
Add x to both sides. You will get an equivalent inequality
x > 1.
It is your
Answer. x > 1.
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The other's tutor writing is incorrect. For your safety, do not consider it as a valid sample.
It is invalid, actually (and unfortunately). Simply ignore it.