Solve 8x + 9 = −7

The solution of 8x + 9 = −7 is x = -2.

8x + 9 = -7\ \Rightarrow\ x = -2

Explain it step by step in chat Make a short video of it

The lines y = 8x + 9 and y = -7 meet at x = -2. 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.
$8x + 9 = -7$
2
Subtract 9 from both sides:
$8x + 9 - 9 = -7 - 9 \ \Rightarrow\ 8x = -16$
3
Divide both sides by 8:
$\frac{8x}{8} = \frac{-16}{8} \ \Rightarrow\ x = -2$
4
Check: put x = -2 back into the equation.
$8\cdot(-2) + 9 = -16 + 9 = -7 \checkmark$

LaTeX source of the formulas on this page

\[ 8x + 9 = -7\ \Rightarrow\ x = -2 \]
\[ 8x + 9 = -7 \]
\[ 8x + 9 - 9 = -7 - 9 \ \Rightarrow\ 8x = -16 \]
\[ \frac{8x}{8} = \frac{-16}{8} \ \Rightarrow\ x = -2 \]
\[ 8\cdot(-2) + 9 = -16 + 9 = -7 \checkmark \]

Trying values of x in 8x + 9 = −7

x	8x + 9	Equals -7?
-4	-23	no
-3	-15	no
-2	-7	yes
-1	1	no
0	9	no

Questions

What is x in 8x + 9 = −7?

The solution of 8x + 9 = −7 is x = -2.

How do you solve 8x + 9 = −7?

Subtract 9 from both sides to get 8x = -16, then divide both sides by 8 to get x = -2.

How do I check the answer?

Replace x by -2: 8(-2) + 9 = -7, which is -7.

Solve 8x + 9 = −7

How to work it out

Trying values of x in 8x + 9 = −7

Questions

Similar equations