The sides of the triangle are given in terms of $x$ and its perimeter is shown. How long is the longest side?

Class 7Simple EquationsSimple Equations

Step-by-Step Solution

x + (x + 3) + (2 x - 1) = 30 \Rightarrow 4 x + 2 = 30 \Rightarrow x = 7

. The sides are 7 cm, 10 cm and

2 (7) - 1 = 13

cm, so the longest is 13 cm. (Stopping at

x = 7

answers the wrong side.)

Answer: C) 13 cm

When the variable appears on both sides, gather all variable terms on one side and all constants on the other.

Example:

5 x + 3 = 2 x + 18

.
Move

2 x

to the left (flip):

5 x - 2 x + 3 = 18

Simplify:

3 x + 3 = 18

Move +3:

3 x = 15

Divide:

x = 5

.

**Verify**:

5 (5) + 3 = 28

;

2 (5) + 18 = 28

✓.

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