let's recall the remainder theorem.
we know that (x-1) is a factor, that means x -1 = 0 or x = 1.
since we know that (x-1) is a factor, then dividing the polynomial by it will give us a remainder of 0, which correlates with saying that f(1) = 0, in this case, so we can simply plug in "1" as the argument, knowing it gives 0.
![f(x)=3x^3+kx-11\\\\[-0.35em]~\dotfill\\\\\stackrel{0}{f(1)}=3(1)^3+k(1)-11\implies \stackrel{f(1)}{0}=3+k-11\implies 0=-8+k\implies 8=k](https://tex.z-dn.net/?f=f%28x%29%3D3x%5E3%2Bkx-11%5C%5C%5C%5C%5B-0.35em%5D~%5Cdotfill%5C%5C%5C%5C%5Cstackrel%7B0%7D%7Bf%281%29%7D%3D3%281%29%5E3%2Bk%281%29-11%5Cimplies%20%5Cstackrel%7Bf%281%29%7D%7B0%7D%3D3%2Bk-11%5Cimplies%200%3D-8%2Bk%5Cimplies%208%3Dk)
18. s = 5r^2 + 7......making r the subject
s - 7 = 5r^2
(s - 7) / 5 = r^2...by taking the sqrt of both sides, it eliminates the ^2
( sqrt (s-7)/5) = r
19. h = ut - 1/2gt^2....u = 100, t = 1 4/5(or 9/5)...g = 6.4
h = (100)(9/5) - 1/2(6.4)(9/5^2)
h = 180 - 1/2(6.4)(3.24)
h = 180 - 3.2(3.24)
h = 180 - 10.368
h = 169.632 or 169 79/125
20. sorry..do not know this one
You have to find out what is the square root of 1.5 is which is <span>1.22474487139 by calculator to make sure of this, do answer squared and you will get 1.5</span>
