(Homework: Quadratic functions) Graph the function and find:
- Type of concavity
- Calculate the axis of symmetry
- Calculate the intercepts with the axes and then check with the graph
- Calculate the vertex of the parabola
- Find the Domain and Range
f(x)=2x²-4x-1

help pls!!

What does x = in this equation x+3+2x=x+5

Grace is standing 18 feet from a lighthouse and kelly is standing 10 feet from grace. the angle that grace looks up to see the top of the lighthouse is 45°. the angle that kelly looks up to see the top of the lighthouse is y°. find the height, h, of the lighthouse. find the angle, rounded to the nearest tenth of a degree, in which kelly looks up to the top of the lighthouse. to the nearest tenth of a degree, find the value of x° . in two or more sentences, explain your calculations

If 0° ≤ θ ≤ 90° and cosθ = 11 15 , what is the value of sin (90° - θ)? a) 11 /15 b) 15/ 11 c) 15 /4 d) 4/15