Solve 3x − 4 = −7

The solution of 3x − 4 = −7 is x = -1.

3x - 4 = -7\ \Rightarrow\ x = -1

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The lines y = 3x − 4 and y = -7 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
The goal is to get x alone. Undo the operations in the opposite order: first the subtraction, then the multiplication.
$3x - 4 = -7$
2
Add 4 to both sides:
$3x - 4 + 4 = -7 + 4 \ \Rightarrow\ 3x = -3$
3
Divide both sides by 3:
$\frac{3x}{3} = \frac{-3}{3} \ \Rightarrow\ x = -1$
4
Check: put x = -1 back into the equation.
$3\cdot(-1) - 4 = -3 - 4 = -7 \checkmark$

LaTeX source of the formulas on this page

\[ 3x - 4 = -7\ \Rightarrow\ x = -1 \]
\[ 3x - 4 = -7 \]
\[ 3x - 4 + 4 = -7 + 4 \ \Rightarrow\ 3x = -3 \]
\[ \frac{3x}{3} = \frac{-3}{3} \ \Rightarrow\ x = -1 \]
\[ 3\cdot(-1) - 4 = -3 - 4 = -7 \checkmark \]

Trying values of x in 3x − 4 = −7

x	3x − 4	Equals -7?
-3	-13	no
-2	-10	no
-1	-7	yes
0	-4	no
1	-1	no

Questions

What is x in 3x − 4 = −7?

The solution of 3x − 4 = −7 is x = -1.

How do you solve 3x − 4 = −7?

Add 4 to both sides to get 3x = -3, then divide both sides by 3 to get x = -1.

How do I check the answer?

Replace x by -1: 3(-1) − 4 = -7, which is -7.

Solve 3x − 4 = −7

How to work it out

Trying values of x in 3x − 4 = −7

Questions

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