Victory for the ACT Student Text 15e

266 • M ATH

Š‡ –Š‡ ͳͲǦ‰ƒŽŽ‘ –ƒ ‘ˆ ƒ ‡‡”‰‡…› ‰‡‡”ƒ–‘” ‹• ϐ‹ŽŽ‡† –‘…ƒ’ƒ…‹–›ǡ –Š‡ ‰‡‡”ƒ–‘” ‘’‡”ƒ–‡• ™‹–Š‘—– ‹–‡””—’–‹‘ ˆ‘” ʹͲ Š‘—”•ǡ…‘•—‹‰ ˆ—‡Ž ƒ– ƒ…‘•–ƒ– rate until all the fuel is consumed. Which ‘ˆ –Š‡ ‰”ƒ’Š• „‡Ž‘™ ”‡’”‡•‡–• –Š‡ ˆ—‡Ž …‘•—’–‹‘ ‘ˆ –Š‡ ‰‡‡”ƒ–‘” ‘˜‡” –‹‡ǫ Ǥ

EXPLANATIONS

19.

19. (C) Mathematics/Algebra and Functions/ Qualitative Behavior of Graphs of Functions Š‡ Ž‘‰‡” –Š‡ ‰‡‡”ƒ–‘” ”—•ǡ –Š‡ ‘”‡ ˆ—‡Ž ‹– —•‡•ǡ ƒ† ȋ Ȍ ‹• –Š‡ ‘Ž› ‰”ƒ’Š –‘ •Š‘™ •—…Š ƒ ”‡Žƒ–‹‘•Š‹’Ǥ ȋ Ȍ ‹• ƒ ‹–‡”‡•–‹‰ ’‘••‹„‹Ž‹–›ǡ „—– ȋ Ȍ •Š‘™• Dz”‡ƒ‹‹‰ ˆ—‡Ždz ‘˜‡” –‹‡ ‘ˆ ‘’‡”ƒ–‹‘ǡ ‘– –Š‡ ˆ—‡Ž ƒŽ”‡ƒ†›…‘•—‡†Ǥ

Throwback to Math Class Š‡ ‡› ’Š”ƒ•‡ in this problem ‹• Dz…‘•–ƒ– ”ƒ–‡Ǥdz This indicates –Šƒ– ˆ‘” ‡˜‡”› unit increase of the input (time), the output (fuel consumption) ‹…”‡ƒ•‡• „› ƒ constant amount. This is a linear relationship, so –Š‡…‘””‡•’‘†‹‰ ‰”ƒ’Š ™‹ŽŽ ƒŽ•‘ be linear.

B.

C.

D.

E.