Problem: If yyy varies directly as xxx and if y=8y=8y=8 when x=4x=4x=4, the value of yyy when x=−8x=-8x=−8 is:
Answer Choices:
A. −16-16−16
B. −4-4−4
C. −2-2−2
D. 4k,k=±1,±2,…4 \mathrm{k}, \mathrm{k}= \pm 1, \pm 2, \ldots4k,k=±1,±2,…
E. 16k,k=±1,±2,…16 \mathrm{k}, \mathrm{k}= \pm 1, \pm 2, \ldots16k,k=±1,±2,… Solution:
y1x1y2x2∴84=y2−8,y2−16\dfrac{y_{1}}{x_{1}} \quad \dfrac{y_{2}}{x_{2}} \quad \therefore \dfrac{8}{4}=\dfrac{y_{2}}{-8}, y_{2}-16x1y1x2y2∴48=−8y2,y2−16