I think it is d. the last one
Answer:
<h2>
11.11 square yard </h2>
Step-by-step explanation:
Step one:
given data
charges=$90
installation=$9 per square yard
total cost of installation= $810
let x represents the number of square feet
Step two:
The expression for the installation cost is given as
810=9x+90------------1
solve for x, collect like terms
810-90=9x
720=9x
divide both sides by 9 we have
x=720/9
x=11.11 square yard
X^2-18 = 3x
x^2 - 3x - 18 = 0
(x-6)(x+3) = 0
x = {-3,6}
So -3 is the answer
Cos 210° = cos ( 180° + 30° ) - cos 30° = - √3/2
