Brianna solved a two-step equation, but she made a mistake along the way.
0.1x + 3 = 1.7
(-3) + 0.1x + 3 = 1.7 + (-3) Line 1
0.1x = -1.3 Line 2
(-0.1) + 0.1x = -1.3 + (-0.1) Line 3
x = -1.4 Line 4
What mistake did Brianna make?
To find the mistake Brianna made, let's go through each step of her solution:
1. Brianna started by subtracting 3 from both sides of the equation, which is correct:
(-3) + 0.1x + 3 = 1.7 + (-3)
2. Next, she simplified the equation by adding the numbers on both sides:
0.1x = -1.3
3. Here is where the mistake occurred. Brianna incorrectly subtracted 0.1 from both sides of the equation. The correct operation should be subtraction, not addition:
(-0.1) + 0.1x = -1.3 + (-0.1)
4. Finally, Brianna correctly simplified the equation:
x = -1.4
Therefore, the mistake Brianna made was adding instead of subtracting 0.1 in line 3.
0.1x + 3 = 1.7
subtract 3 from both sides
0.1x + 3 -3 = 1.7-3
.1x = -1.3
divide both sides by .1
.1x /.1 = -1.3/.1
x = -13
You establish where her error was.