One more than three times a number is the same as four less than double a number
1 answer:
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Answer:
See the attached figure which represents the problem.
As shown, AA₁ and BB₁ are the altitudes in acute △ABC.
△AA₁C is a right triangle at A₁
So, Cos x = adjacent/hypotenuse = A₁C/AC ⇒(1)
△BB₁C is a right triangle at B₁
So, Cos x = adjacent/hypotenuse = B₁C/BC ⇒(2)
From (1) and (2)
∴ A₁C/AC = B₁C/BC
using scissors method
∴ A₁C · BC = B₁C · AC
To start, we're given the range that x lies in: from -1 to 4. We know from the fact that 
that -1 will be <em /><em>included</em> in that range, so we mark -1 on the number line with a solid circle. We also know from 
that, while x can be any value <em>up to</em> 4, it does not <em>include </em>4. We indicate this by drawing a hollow circle around 4 on the number line. Since x can be <em>any value within this range</em>, we make that fact clear by drawing a bold line between the points -1 and 4 on the number line. I've attached an image of what our final graph would look like.
