Choose which expression doesn’t belong? State your reasoning.

Step-by-step explanation:

This warm-up prompts students to carefully analyze and compare quadratic expressions. In making comparisons, students need to look for common structure and have a reason to use language precisely (MP7, MP6). The activity also enables the teacher to hear the terminology students know and how they talk about characteristics of the different forms of expressions.

As students discuss in groups, listen for rationales that are based on the structure of the expressions. Select those students or groups to share their thinking during class discussion.

Launch

Arrange students in groups of 2–4. Display the expressions for all to see. Give students 1 minute of quiet think time and then time to share their thinking with their small group. In their small groups, ask each student to share their reasoning about why a particular item does not belong, and together find at least one reason each item doesn't belong.

Student Facing

Which one doesn’t belong?

A.

B.

C.

c.   x=2.4cm

step-by-step explanation:

similar triangles are triangles which have the same shape but not the same size. this means their angle measures are equal but their side lengths are not instead they are proportional. to solve, we will set up a proportion and solve.

a proportion is two equal ratios set equal to each other. we form the ratios by finding corresponding sides (sides which match to each other on both triangles by their position). out ratios will be one side of the small triangle over the corresponding side on the big triangle as shown below:

.

to solve the proportion, we'll cross multiply by multiplying numerator with denominator across the equal sign.