Find the sets on which f(x)>0 and f(x)<0 on the given domain. Express in interval notation. Make sure for numbers such as 2π you type in 2*pi and for 3π2 you type in 3*pi/2. For any unused answer boxes type in DNE in all capital letters.
f(x)=7cos(5x) on (0,4π/5)
f(x) >0 on (0,pi/10)u(3pi/10,9pi/10)u(7pi/10, 4pi/5)
f(x) <0 on (pi/10, 3pi/10)u(9pi/10, 7pi/10)
is this correct>
Thanks