Solve 4x + 15 = −17

The solution of 4x + 15 = −17 is x = -8.

4x + 15 = -17\ \Rightarrow\ x = -8

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The lines y = 4x + 15 and y = -17 meet at x = -8. 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.
$4x + 15 = -17$
2
Subtract 15 from both sides:
$4x + 15 - 15 = -17 - 15 \ \Rightarrow\ 4x = -32$
3
Divide both sides by 4:
$\frac{4x}{4} = \frac{-32}{4} \ \Rightarrow\ x = -8$
4
Check: put x = -8 back into the equation.
$4\cdot(-8) + 15 = -32 + 15 = -17 \checkmark$

LaTeX source of the formulas on this page

\[ 4x + 15 = -17\ \Rightarrow\ x = -8 \]
\[ 4x + 15 = -17 \]
\[ 4x + 15 - 15 = -17 - 15 \ \Rightarrow\ 4x = -32 \]
\[ \frac{4x}{4} = \frac{-32}{4} \ \Rightarrow\ x = -8 \]
\[ 4\cdot(-8) + 15 = -32 + 15 = -17 \checkmark \]

Trying values of x in 4x + 15 = −17

x	4x + 15	Equals -17?
-10	-25	no
-9	-21	no
-8	-17	yes
-7	-13	no
-6	-9	no

Questions

What is x in 4x + 15 = −17?

The solution of 4x + 15 = −17 is x = -8.

How do you solve 4x + 15 = −17?

Subtract 15 from both sides to get 4x = -32, then divide both sides by 4 to get x = -8.

How do I check the answer?

Replace x by -8: 4(-8) + 15 = -17, which is -17.

Solve 4x + 15 = −17

How to work it out

Trying values of x in 4x + 15 = −17

Questions

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