WordGPT

Solve 8x + 9 = 129

The solution of 8x + 9 = 129 is x = 15.

Explain it step by step in chatMake a short video of it
The lines y = 8x + 9 and y = 129 meet at x = 1510121416182080100120140160180x = 15y = 8x + 9y = 129
The lines y = 8x + 9 and y = 129 meet at x = 15. 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+9=1298x + 9 = 129
  2. 2

    Subtract 9 from both sides:

    8x+9−9=129−9 ⇒ 8x=1208x + 9 - 9 = 129 - 9 \ \Rightarrow\ 8x = 120
  3. 3

    Divide both sides by 8:

    8x8=1208 ⇒ x=15\frac{8x}{8} = \frac{120}{8} \ \Rightarrow\ x = 15
  4. 4

    Check: put x = 15 back into the equation.

    8⋅15+9=120+9=129✓8\cdot15 + 9 = 120 + 9 = 129 \checkmark
LaTeX source of the formulas on this page
\[ 8x + 9 = 129\ \Rightarrow\ x = 15 \]
\[ 8x + 9 = 129 \]
\[ 8x + 9 - 9 = 129 - 9 \ \Rightarrow\ 8x = 120 \]
\[ \frac{8x}{8} = \frac{120}{8} \ \Rightarrow\ x = 15 \]
\[ 8\cdot15 + 9 = 120 + 9 = 129 \checkmark \]

Trying values of x in 8x + 9 = 129

x8x + 9Equals 129?
13113no
14121no
15129yes
16137no
17145no

Questions

What is x in 8x + 9 = 129?

The solution of 8x + 9 = 129 is x = 15.

How do you solve 8x + 9 = 129?

Subtract 9 from both sides to get 8x = 120, then divide both sides by 8 to get x = 15.

How do I check the answer?

Replace x by 15: 8(15) + 9 = 129, which is 129.

Similar equations

    Solve 8x + 9 = 129: x = 15 (steps and check) | WordGPT