#### Race (Intermediate-Modelling )

Three friends decided to take a run. Ana used a bicycle, Filipa and Joana used cars. Joana's car is faster than Filipa's. Each function of the figure corresponds to the race of each of the friends. The expression $g(5)=125$ means that:

# Linear functions

Modeling
9

#### Devaluation of a product (E_M)

Due to wear, the value (V) of a product decrease with time (t). We can then consider the devaluation of a product as a linear function. Knowing that the value of a machine today is 1000 euros, and estimating that in 5 years it will be 250 euros, what will its total devaluation be after 6 years?

# Linear functions

Modeling
9

#### Positive and negative slopes

Can you identify which slopes are positive and which are negative? Select all and only those graphs that have positive slopes.

# Linear functions

Training
8

#### From table to law

If x and y of the table are proportional, find the law of a proportional function that fits to the data given in the table.

# Unassigned

Training
8

#### Intersection of linear functions

a) Calculate the point of intersection of the following two lines. Round to two decimal places for the input. function 1: $y_1 = -1,5x + 3$ function 2: $y_2 = 3x + 6$ b) Calculate how the parameter $m$ of the line $y_3$ must be chosen so that the two lines $y_3$ and $y_4$ intersect at the position $x_0=3$. Round to two decimal places for the input. function 1: $y_3 = m⋅x+3$ function 2: $y_4 = -2,5x + 10$

# Linear functions

Training
8