Question 316·Easy·Algebra

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If $4x + 9 = 25$ , what value of $x$ satisfies the equation?

Your answer

A linear equation with one unknown asks for the value that makes both sides equal. Undo addition on both sides to expose the term containing the unknown, then use a Desmos regression to find its value. The key trap is stopping when you’ve found a value for the whole term rather than for the unknown itself.

Hints

Hint 1
The $9$ is added to the part containing $x$ . Subtract $9$ from both sides so they stay equal. What’s left on the side with $x$ ?
Hint 2
A coefficient is the number multiplying a variable. Here, $4x$ means $4$ times $x$ , so the value of $4x$ is not yet the value of $x$ .

Step-by-step

Subtract, then solve in Desmos
Step 1
Remove the added 9
The $9$ is added to $4x$ , so subtract $9$ from both sides to keep them equal:
$4x+9-9=25-9$ $4x=16$
You’ve found the value of $4x$ , not yet the value of $x$ .
Step 2
Find the value of x
Type the original equation as $4x_1+9\sim25$ in Desmos. Use $x_1$ for the unknown and $\sim$ to tell Desmos to find a value that makes the sides equal. Under PARAMETERS, it shows $x_1=4$ . So the value of $x$ that satisfies the equation is $4$ . Grid in 4.

Question 316·Easy·Algebra

Strategy

Hints

Step-by-step

Lessons that teach this

Study Hints

Strategy

Hints

Step-by-step

Lessons that teach this