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Solve 8x + 13 = 21

The solution of 8x + 13 = 21 is x = 1.

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The lines y = 8x + 13 and y = 21 meet at x = 1-4-2246-20204060x = 1y = 8x + 13y = 21
The lines y = 8x + 13 and y = 21 meet at x = 1. 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.

    8x+13=218x + 13 = 21
  2. 2

    Subtract 13 from both sides:

    8x+13−13=21−13 ⇒ 8x=88x + 13 - 13 = 21 - 13 \ \Rightarrow\ 8x = 8
  3. 3

    Divide both sides by 8:

    8x8=88 ⇒ x=1\frac{8x}{8} = \frac{8}{8} \ \Rightarrow\ x = 1
  4. 4

    Check: put x = 1 back into the equation.

    8⋅1+13=8+13=21✓8\cdot1 + 13 = 8 + 13 = 21 \checkmark
LaTeX source of the formulas on this page
\[ 8x + 13 = 21\ \Rightarrow\ x = 1 \]
\[ 8x + 13 = 21 \]
\[ 8x + 13 - 13 = 21 - 13 \ \Rightarrow\ 8x = 8 \]
\[ \frac{8x}{8} = \frac{8}{8} \ \Rightarrow\ x = 1 \]
\[ 8\cdot1 + 13 = 8 + 13 = 21 \checkmark \]

Trying values of x in 8x + 13 = 21

x8x + 13Equals 21?
-15no
013no
121yes
229no
337no

Questions

What is x in 8x + 13 = 21?

The solution of 8x + 13 = 21 is x = 1.

How do you solve 8x + 13 = 21?

Subtract 13 from both sides to get 8x = 8, then divide both sides by 8 to get x = 1.

How do I check the answer?

Replace x by 1: 8(1) + 13 = 21, which is 21.

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    Solve 8x + 13 = 21: x = 1 (steps and check) | WordGPT