Solve 8x + 11 = −21

The solution of 8x + 11 = −21 is x = -4.

8x + 11 = -21\ \Rightarrow\ x = -4

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The lines y = 8x + 11 and y = -21 meet at x = -4. 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.
$8x + 11 = -21$
2
Subtract 11 from both sides:
$8x + 11 - 11 = -21 - 11 \ \Rightarrow\ 8x = -32$
3
Divide both sides by 8:
$\frac{8x}{8} = \frac{-32}{8} \ \Rightarrow\ x = -4$
4
Check: put x = -4 back into the equation.
$8\cdot(-4) + 11 = -32 + 11 = -21 \checkmark$

LaTeX source of the formulas on this page

\[ 8x + 11 = -21\ \Rightarrow\ x = -4 \]
\[ 8x + 11 = -21 \]
\[ 8x + 11 - 11 = -21 - 11 \ \Rightarrow\ 8x = -32 \]
\[ \frac{8x}{8} = \frac{-32}{8} \ \Rightarrow\ x = -4 \]
\[ 8\cdot(-4) + 11 = -32 + 11 = -21 \checkmark \]

Trying values of x in 8x + 11 = −21

x	8x + 11	Equals -21?
-6	-37	no
-5	-29	no
-4	-21	yes
-3	-13	no
-2	-5	no

Questions

What is x in 8x + 11 = −21?

The solution of 8x + 11 = −21 is x = -4.

How do you solve 8x + 11 = −21?

Subtract 11 from both sides to get 8x = -32, then divide both sides by 8 to get x = -4.

How do I check the answer?

Replace x by -4: 8(-4) + 11 = -21, which is -21.

Solve 8x + 11 = −21

How to work it out

Trying values of x in 8x + 11 = −21

Questions

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