Question

Two problems I need help on:
Given the point (2, 3) and the slope of 4, find y when x = 22.

78

83

88

91
And
Given the function f(x) = 4(x+3) − 5, solve for the inverse function when x = 3.

−21

−16

−10

−1

Answer 1

y = mx + b

3 = 4(2) + b
3 = 8 + b
3 - 8 = b
-5 = b

So m = 4 and b = -5 so

y = 4x - 5

When x = 22:

y = 4(22) - 5
y = 88 - 5
y = 83

Answer 2

Oh okay... so would that work for the second one, even though its asking for the inverse?

Answer 3

oh wait no...because its not the same set up, it already has the equations set up

Answer 4

so would I do (3)=4(3-3)-5 Because its asking for the inverse?

Answer 5

or (3)=4(3-3)+5

Answer 6

Okay, yeah, you have to find the inverse first.

Answer 7

f(x) = 4(x + 3) - 5

Change f(x) to y:

y = 4(x + 3) - 5

Swap x and y:

x = 4(y + 3) - 5

Isolate y:

x + 5 = 4(y + 3)

\(\dfrac{x + 5}{4} = y + 3\)

Now input x = 3:

\(\dfrac{x + 5}{4} - 3 = y\)

\(\dfrac{3 + 5}{4} - 3= y \)

Answer 8

okay I'm doing something wrong...I keep getting 1.25, but that's not a option

Answer 9

\(\dfrac{8}{4} - 3 = y\)

\(2 - 3 = y\)

\(-1 = y\)

Answer 10

Okay, just got that...my calculator was being dumb! Thanks ^-^

Answer 11

You should be able to do it without a calculator.