## Calculus: Early Transcendentals 8th Edition

Given: $r(t)=t^{3}i+2t^{3}j+3t^{3}k$ All three $i,j,k$ increase linearly in relation to each other if we put $t^{3}=x$ $r(x)=xi+2xj+3xk$ Since all the coefficients are linear in $x$ this forms a line. Hence, the statement is true.