Hey guys,
How does (d-6)^2 - 4 < 0
become 4 < d < 8 ?
im confused with the individual steps
Hey! There are heaps of ways of going about this, but this is how I generally work through these kinds of questions. Let me know if you don't understand any steps!
Now, I usually work out inequalities by first solving an equation. As such,
So, we now have two solutions for d. The range will either be OUTSIDE (ie. d>8, d<4) or INSIDE (ie. 4<d<8 ). You can figure this out in a number of ways; the easiest is to sub in a point to the original equation. Let's say that d is equal to 5.
Clearly, the relationship is true for d=5, which is between 4 and 8. Therefore, the solution for d is
As required!
Jake