Solve 8x + 9 = −47

The solution of 8x + 9 = −47 is x = -7.

8x + 9 = -47\ \Rightarrow\ x = -7

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The lines y = 8x + 9 and y = -47 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 addition, then the multiplication.
$8x + 9 = -47$
2
Subtract 9 from both sides:
$8x + 9 - 9 = -47 - 9 \ \Rightarrow\ 8x = -56$
3
Divide both sides by 8:
$\frac{8x}{8} = \frac{-56}{8} \ \Rightarrow\ x = -7$
4
Check: put x = -7 back into the equation.
$8\cdot(-7) + 9 = -56 + 9 = -47 \checkmark$

LaTeX source of the formulas on this page

\[ 8x + 9 = -47\ \Rightarrow\ x = -7 \]
\[ 8x + 9 = -47 \]
\[ 8x + 9 - 9 = -47 - 9 \ \Rightarrow\ 8x = -56 \]
\[ \frac{8x}{8} = \frac{-56}{8} \ \Rightarrow\ x = -7 \]
\[ 8\cdot(-7) + 9 = -56 + 9 = -47 \checkmark \]

Trying values of x in 8x + 9 = −47

x	8x + 9	Equals -47?
-9	-63	no
-8	-55	no
-7	-47	yes
-6	-39	no
-5	-31	no

Questions

What is x in 8x + 9 = −47?

The solution of 8x + 9 = −47 is x = -7.

How do you solve 8x + 9 = −47?

Subtract 9 from 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) + 9 = -47, which is -47.

Solve 8x + 9 = −47

How to work it out

Trying values of x in 8x + 9 = −47

Questions

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