Writing a Function Rule

y is 5 less than the product of 4 and x

• y = 4x - 5

• y < 4x

• y = 5 - 4x

• y + 5 = 4x

Tags

CCSS.8.EE.C.7

CCSS.8.F.A.1

CCSS.8.F.B.4

c is 8 more than half of n

• C = 8 + 2n

• C = 8 - 2n

• C = 8 + ½ n

• C > 8 + n/2

Tags

CCSS.8.EE.C.7

CCSS.8.F.A.1

CCSS.8.F.A.3

CCSS.8.F.B.4

7 less than three fifths of b is a.

• 7 < ⅗ b + a

• 7 - ⅗ b = a

• 7 - ⅗ ÷ b = a

• ⅗ b - 7 = a

Tags

CCSS.8.EE.C.7

2.5 more than the quotient of h and 3 is w

• 3h + 2.5 = w

• 2.5 + h/3 = w

• w = 3h - 2.5

• 2.5h + ⅓ = 2.5

Tags

CCSS.8.EE.C.7

CCSS.8.F.B.4

The almond extract a remaining in an 8-oz bottle decreases by 1/6 oz for each batch b of waffle cookies made. Make a function rule.

• a = 8 - ⅙ b

• a = ⅙ b

• a = 6b

• b = 6a

Tags

CCSS.8.EE.B.6

CCSS.8.F.A.1

CCSS.8.F.B.4

A helicopter hovers 40 ft above the ground, then it climbs at a rate of 21 ft/sec. Write a rule for its height h as a function of time t seconds. Then find its height after 45 seconds.

• h(t) = 40 + 21 and 61 ft

• h(t) = 61t and 2745 ft

• h(t) = 21 + 40t and 1821 ft

• h(t) = 40 + 21t and 985 ft

Tags

CCSS.8.EE.B.6

CCSS.8.F.A.1

CCSS.8.F.A.3

CCSS.8.F.B.4

A team of divers gathers at an elevation of -10 ft. Then the team dives at a rate of -50 ft/min. Write a function rule for the depth d of the divers as a function of time t minutes. Then find their depth after 3 minutes.

• d = -10 - 50t and -160 ft

• d = 10 - 50t and -140 ft

• d = 10 + 50t and 160 ft

• d = -10t - 50 and -80 ft

Tags

CCSS.8.EE.B.6

CCSS.8.F.A.1

CCSS.8.F.A.3

CCSS.8.F.B.4

A new book is being planned. It will have 24 pages of introduction, followed by c 12-page chapters, and then 48 pages at the end of the book. Write a rule for the total pages p of the book. Then find the number of pages if there are 25 chapters.

• p = 12c and 300 pages

• p = 72 + 12c and 372 pages

• p = 72c + 12 and 4557 pages

• p = 72 + 12 and 84 pages

Tags

CCSS.8.EE.C.7

CCSS.8.F.A.1

CCSS.8.F.B.4

You go to dinner and leave a 15% tip for your server. In your wallet, you only have $55. Write a function rule for the amount of money you would have left m if the meal costs x dollars before the tip

• m(x) = 55 - c

• m(x) = 55 − c − 0.15c

• m(x) = c + 55

• m(x) = c - 55 + 0.15

Tags

CCSS.8.F.A.1

CCSS.8.F.A.2

CCSS.8.F.B.4

Assuming you pay the 15% tip, would you have enough money to buy a meal that costs $45? If so, how much money m would you have left?

• yes, $10

• no

• yes, $7.75

• yes, $3.25

Tags

CCSS.7.EE.B.3

CCSS.7.RP.A.3