=−640x10+1280x9+19904x8−40728x7−144488x6+323904x5−162304x4+1024x3+2048x2
step by step
(2x+8x2+3x−4x(x−4)(x−1)(20)x+4)(2)(x+4)(x−4)(2)x(x−1)(2)x(x+4)
=((2x+8x2+3x−4x(x−4)(x−1)(20)x+4)(2)(x+4)(x−4)(2)x(x−1)(2)x)(x+4)
=((2x+8x2+3x−4x(x−4)(x−1)(20)x+4)(2)(x+4)(x−4)(2)x(x−1)(2)x)(x)+((2x+8x2+3x−4x(x−4)(x−1)(20)x+4)(2)(x+4)(x−4)(2)x(x−1)(2)x)(4)
=−640x10+3840x9+4544x8−58904x7+91128x6−40608x5+128x4+512x3−2560x9+15360x8+18176x7−235616x6+364512x5−162432x4+512x3+2048x2
=−640x10+1280x9+19904x8−40728x7−144488x6+323904x5−162304x4+1024x3+2048x2
You want to find the value of x for which the area under the curve to the left of x is 0.6. One way to do that is to create the cumulative distribution function (CDF) for the given PDF, then see where it is equal to 0.6.
Doing that, we find a = 5.
We can't see the table but if every input or x has only one specific output or y then it is a function so if every different height has one number of stories then it's a function you can have it though to were say you have 18 feet and 17 feet and they are both 3 stories then it's still a function but if you have 18 feet thats 3 stories and 18 feet thats 4 stories then its not a function
