Solve 8x − 5 = 51

The solution of 8x − 5 = 51 is x = 7.

8x - 5 = 51\ \Rightarrow\ x = 7

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The lines y = 8x − 5 and y = 51 meet at x = 7. 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 subtraction, then the multiplication.
$8x - 5 = 51$
2
Add 5 to both sides:
$8x - 5 + 5 = 51 + 5 \ \Rightarrow\ 8x = 56$
3
Divide both sides by 8:
$\frac{8x}{8} = \frac{56}{8} \ \Rightarrow\ x = 7$
4
Check: put x = 7 back into the equation.
$8\cdot7 - 5 = 56 - 5 = 51 \checkmark$

LaTeX source of the formulas on this page

\[ 8x - 5 = 51\ \Rightarrow\ x = 7 \]
\[ 8x - 5 = 51 \]
\[ 8x - 5 + 5 = 51 + 5 \ \Rightarrow\ 8x = 56 \]
\[ \frac{8x}{8} = \frac{56}{8} \ \Rightarrow\ x = 7 \]
\[ 8\cdot7 - 5 = 56 - 5 = 51 \checkmark \]

Trying values of x in 8x − 5 = 51

x	8x − 5	Equals 51?
5	35	no
6	43	no
7	51	yes
8	59	no
9	67	no

Questions

What is x in 8x − 5 = 51?

The solution of 8x − 5 = 51 is x = 7.

How do you solve 8x − 5 = 51?

Add 5 to both sides to get 8x = 56, then divide both sides by 8 to get x = 7.

How do I check the answer?

Replace x by 7: 8(7) − 5 = 51, which is 51.

Solve 8x − 5 = 51

How to work it out

Trying values of x in 8x − 5 = 51

Questions

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