Math 1 · Unit 7 · Lesson 2 · part 1 of 6

The Words We Use

The vocabulary for this lesson, in one place.

Words we use

Word	Plain English	What you do
Family, member, parameter	The exponential family shares the form y = a · b^x; each member is picked out by its own a and b.	Name the family, find its numbers, say what each does.
Initial value (starting value), a	The output when x = 0. Also the y-intercept, because b⁰ = 1 and a · 1 = a.	Read it as the number in front. Start the table here.
Growth factor, b	The number you multiply by each step: the constant ratio down the table.	Read it as the base. Multiply by it for each step right.
y-intercept	Where the curve crosses the y-axis: (0, a).	Same idea as b in y = mx + b.
Power first	In a · b^x, work out b^x before multiplying by a.	3 · 2⁴ = 3 · 16 = 48.
Invisible 1	y = 2^x means y = 1 · 2^x: a = 1.	Same invisible 1 as Unit 1.