1. what is the perimeter of a rectangle with length 12 cm and width 5 cm?
2. solve: 3x + 7 = 28
3. evaluate when a = 4: 2a² + 3a

Question

Accepted Answer

# Explanation:
## 1. Calculate the perimeter of the rectangle
### Step1: Recall the formula for the perimeter of a rectangle
The formula for the perimeter $P$ of a rectangle is $P = 2(l + w)$, where $l$ is the length and $w$ is the width.
### Step2: Substitute the given values into the formula
Given $l=12$ cm and $w = 5$ cm.
$$
\begin{align*}
P&=2(12 + 5)\
&=2\times17\
&=34
\end{align*}
$$

## 2. Solve the equation $3x+7 = 28$
### Step1: Isolate the term with $x$
Subtract $7$ from both sides of the equation:
$$
\begin{align*}
3x+7-7&=28 - 7\
3x&=21
\end{align*}
$$
### Step2: Solve for $x$
Divide both sides by $3$:
$$
\begin{align*}
\frac{3x}{3}&=\frac{21}{3}\
x&=7
\end{align*}
$$

## 3. Evaluate $2a^{2}+3a$ when $a = 4$
### Step1: Substitute $a = 4$ into the expression
$$
\begin{align*}
2a^{2}+3a&=2\times4^{2}+3\times4
\end{align*}
$$
### Step2: Calculate the powers
$$
\begin{align*}
2\times4^{2}+3\times4&=2\times16+3\times4
\end{align*}
$$
### Step3: Perform the multiplications
$$
\begin{align*}
2\times16+3\times4&=32 + 12
\end{align*}
$$
### Step4: Perform the addition
$$
\begin{align*}
32+12&=44
\end{align*}
$$

# Answer:
1. $34$ cm
2. $x = 7$
3. $44$

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QUESTION IMAGE

Question

Explanation:

1. Calculate the perimeter of the rectangle

Step1: Recall the formula for the perimeter of a rectangle

Step2: Substitute the given values into the formula

2. Solve the equation \(3x+7 = 28\)

Step1: Isolate the term with \(x\)

Step2: Solve for \(x\)

3. Evaluate \(2a^{2}+3a\) when \(a = 4\)

Step1: Substitute \(a = 4\) into the expression

Step2: Calculate the powers

Step3: Perform the multiplications

Step4: Perform the addition

Answer: