Solve 7x − 7 = −28

The solution of 7x − 7 = −28 is x = -3.

7x - 7 = -28\ \Rightarrow\ x = -3

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The lines y = 7x − 7 and y = -28 meet at x = -3. 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.
$7x - 7 = -28$
2
Add 7 to both sides:
$7x - 7 + 7 = -28 + 7 \ \Rightarrow\ 7x = -21$
3
Divide both sides by 7:
$\frac{7x}{7} = \frac{-21}{7} \ \Rightarrow\ x = -3$
4
Check: put x = -3 back into the equation.
$7\cdot(-3) - 7 = -21 - 7 = -28 \checkmark$

LaTeX source of the formulas on this page

\[ 7x - 7 = -28\ \Rightarrow\ x = -3 \]
\[ 7x - 7 = -28 \]
\[ 7x - 7 + 7 = -28 + 7 \ \Rightarrow\ 7x = -21 \]
\[ \frac{7x}{7} = \frac{-21}{7} \ \Rightarrow\ x = -3 \]
\[ 7\cdot(-3) - 7 = -21 - 7 = -28 \checkmark \]

Trying values of x in 7x − 7 = −28

x	7x − 7	Equals -28?
-5	-42	no
-4	-35	no
-3	-28	yes
-2	-21	no
-1	-14	no

Questions

What is x in 7x − 7 = −28?

The solution of 7x − 7 = −28 is x = -3.

How do you solve 7x − 7 = −28?

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

How do I check the answer?

Replace x by -3: 7(-3) − 7 = -28, which is -28.

Solve 7x − 7 = −28

How to work it out

Trying values of x in 7x − 7 = −28

Questions

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