Solve 3x − 4 = 17

The solution of 3x − 4 = 17 is x = 7.

3x - 4 = 17\ \Rightarrow\ x = 7

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The lines y = 3x − 4 and y = 17 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.
$3x - 4 = 17$
2
Add 4 to both sides:
$3x - 4 + 4 = 17 + 4 \ \Rightarrow\ 3x = 21$
3
Divide both sides by 3:
$\frac{3x}{3} = \frac{21}{3} \ \Rightarrow\ x = 7$
4
Check: put x = 7 back into the equation.
$3\cdot7 - 4 = 21 - 4 = 17 \checkmark$

LaTeX source of the formulas on this page

\[ 3x - 4 = 17\ \Rightarrow\ x = 7 \]
\[ 3x - 4 = 17 \]
\[ 3x - 4 + 4 = 17 + 4 \ \Rightarrow\ 3x = 21 \]
\[ \frac{3x}{3} = \frac{21}{3} \ \Rightarrow\ x = 7 \]
\[ 3\cdot7 - 4 = 21 - 4 = 17 \checkmark \]

Trying values of x in 3x − 4 = 17

x	3x − 4	Equals 17?
5	11	no
6	14	no
7	17	yes
8	20	no
9	23	no

Questions

What is x in 3x − 4 = 17?

The solution of 3x − 4 = 17 is x = 7.

How do you solve 3x − 4 = 17?

Add 4 to both sides to get 3x = 21, then divide both sides by 3 to get x = 7.

How do I check the answer?

Replace x by 7: 3(7) − 4 = 17, which is 17.

Solve 3x − 4 = 17

How to work it out

Trying values of x in 3x − 4 = 17

Questions

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