Do you mean <span><span><span><span>cos6</span>x+6<span>cos4</span>x+15<span>cos2</span>x+10</span><span><span>cos5</span>x+5<span>cos3</span>x+10cosx</span></span> ?</span>
or <span><span><span>cos6x+6cos4x+15cos2x+10</span><span>cos5x+5cos3x+10cosx</span></span> ?</span>
or <span><span><span><span>cos6</span>x+6<span>cos4</span>x+15<span>cos2</span>x+10</span><span><span>cos5</span>x</span></span>+5<span>cos3</span>x+10cosx ?</span>
or <span><span><span>cos6x+6cos4x+15cos2x+10</span><span>cos5x</span></span>+5cos3x+10cosx <span>?</span></span>
Make sure you study, and if necessary, do some practice problems. Then, check to make sure you are right, and if not, find out why, and correct your mistakes.