Method 1: Select "Vector Matrix" under "Style" to modify it. The specific steps are as follows:

1. Enter a+b in the editing area;

2. Select the letter A and select "Vector Matrix" under the "Style" menu;

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3. At this time, the letter A is bold, indicating the vector A..

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4. We can learn from the above steps of thickening vector A and input the rest of the equation.