If r varies jointly as p and q and inversely as t, then how do you find an equation for r if r=6 when p=8, q=−3, and t=3?

1 Answer
Jul 30, 2017

r=-(3pq)/(4t)r=3pq4t

Explanation:

"the initial statement is "rprop(pq)/tthe initial statement is rpqt

"to convert to an equation multiply by k the constant"to convert to an equation multiply by k the constant
"of variation"of variation

rArrr=(kpq)/tr=kpqt

"to find k use the given condition"to find k use the given condition

r=6" when "p=8,q=-3" and "t=3r=6 when p=8,q=3 and t=3

r=(kpq)/tr=kpqt

rArrkpq=rtlarrcolor(blue)" cross-multiplying"kpq=rt cross-multiplying

rArrk=(rt)/(pq)=(6xx3)/(8xx-3)=18/(-24)=-3/4k=rtpq=6×38×3=1824=34

rArr" equation is " color(red)(bar(ul(|color(white)(2/2)color(black)(r=-(3pq)/(4t)color(white)(2/2)|)))