(i think i know it just checking) which function has a period equal to half the period of the function in y=5cos(3/5x-pi)+4.. the period is 10pi/3

i think its the first one.

1. y=5sin(6/5x-pi)-4
2. y=-5/2sin(6/10x-2pi)+1/2
3. y=-4cos(5/6x-2pi)+5
4. y=2cos(3/10x-pi)-5/2

What is the equation of a parabola y(x) that has a vertex at point (− 1/3 , 0.3) and passes through point (− 2/15 , − 1/2 ).

White shapes and black shapes are used in a game. some of the shapes are circles. while the rest are squares. the ratio of the number of white shapes to the number of black shapes is 5: 11. the ratio of the number of white cicrles to the number of white squares is 3: 7. the ratio of the number of black circles to the number of black squres is 3: 8. work out what fraction of all the shapes are circles.

Maria solved an equation as shown below. what is the solution to maria’s equation?