Solve 8x + 13 = 45

The solution of 8x + 13 = 45 is x = 4.

8x + 13 = 45\ \Rightarrow\ x = 4

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The lines y = 8x + 13 and y = 45 meet at x = 4. The solution of the equation is the x-coordinate of the point where the two sides are equal.

How to work it out

1
The goal is to get x alone. Undo the operations in the opposite order: first the addition, then the multiplication.
$8x + 13 = 45$
2
Subtract 13 from both sides:
$8x + 13 - 13 = 45 - 13 \ \Rightarrow\ 8x = 32$
3
Divide both sides by 8:
$\frac{8x}{8} = \frac{32}{8} \ \Rightarrow\ x = 4$
4
Check: put x = 4 back into the equation.
$8\cdot4 + 13 = 32 + 13 = 45 \checkmark$

LaTeX source of the formulas on this page

\[ 8x + 13 = 45\ \Rightarrow\ x = 4 \]
\[ 8x + 13 = 45 \]
\[ 8x + 13 - 13 = 45 - 13 \ \Rightarrow\ 8x = 32 \]
\[ \frac{8x}{8} = \frac{32}{8} \ \Rightarrow\ x = 4 \]
\[ 8\cdot4 + 13 = 32 + 13 = 45 \checkmark \]

Trying values of x in 8x + 13 = 45

x	8x + 13	Equals 45?
2	29	no
3	37	no
4	45	yes
5	53	no
6	61	no

Questions

What is x in 8x + 13 = 45?

The solution of 8x + 13 = 45 is x = 4.

How do you solve 8x + 13 = 45?

Subtract 13 from both sides to get 8x = 32, then divide both sides by 8 to get x = 4.

How do I check the answer?

Replace x by 4: 8(4) + 13 = 45, which is 45.

Solve 8x + 13 = 45

How to work it out

Trying values of x in 8x + 13 = 45

Questions

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