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Solve 6x + 9 = 21

The solution of 6x + 9 = 21 is x = 2.

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The lines y = 6x + 9 and y = 21 meet at x = 2-4-22468-20-10102030405060x = 2y = 6x + 9y = 21
The lines y = 6x + 9 and y = 21 meet at x = 2. The solution of the equation is the x-coordinate of the point where the two sides are equal.

How to work it out

  1. 1

    The goal is to get x alone. Undo the operations in the opposite order: first the addition, then the multiplication.

    6x+9=216x + 9 = 21
  2. 2

    Subtract 9 from both sides:

    6x+9−9=21−9 ⇒ 6x=126x + 9 - 9 = 21 - 9 \ \Rightarrow\ 6x = 12
  3. 3

    Divide both sides by 6:

    6x6=126 ⇒ x=2\frac{6x}{6} = \frac{12}{6} \ \Rightarrow\ x = 2
  4. 4

    Check: put x = 2 back into the equation.

    6⋅2+9=12+9=21✓6\cdot2 + 9 = 12 + 9 = 21 \checkmark
LaTeX source of the formulas on this page
\[ 6x + 9 = 21\ \Rightarrow\ x = 2 \]
\[ 6x + 9 = 21 \]
\[ 6x + 9 - 9 = 21 - 9 \ \Rightarrow\ 6x = 12 \]
\[ \frac{6x}{6} = \frac{12}{6} \ \Rightarrow\ x = 2 \]
\[ 6\cdot2 + 9 = 12 + 9 = 21 \checkmark \]

Trying values of x in 6x + 9 = 21

x6x + 9Equals 21?
09no
115no
221yes
327no
433no

Questions

What is x in 6x + 9 = 21?

The solution of 6x + 9 = 21 is x = 2.

How do you solve 6x + 9 = 21?

Subtract 9 from both sides to get 6x = 12, then divide both sides by 6 to get x = 2.

How do I check the answer?

Replace x by 2: 6(2) + 9 = 21, which is 21.

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    Solve 6x + 9 = 21: x = 2 (steps and check) | WordGPT