Note: Each answer output occupies one line

If the result of $-5x (x ^ 2+a)+10x+2$does not contain the $x$term, then a=__.

{{ select(1) }}

• 2
• 5
• -2
• -10

The arithmetic square root of $9 is __.

{{ select(2) }}

• 81
• ±3
• 9
• 3

3. Write the answer directly: $(4x ^ 5+3x) ÷ x - (2x ^ 2) ^ 2=${{input (3)}}

4. Write the answer directly: $(ab+6) ^ 2=${{input (4)}}

• Format requirement: Formula: $(x+y) ^ 2=x ^ 2+y ^ 2+2xy$, where $a ^ 2$is written as: a ^ 2 ````

{{ select(5) }}

• 6
• 10
• 15
• 16

6. As shown in Figure 6, take the sides AC and BC of △ ABC as sides, and draw squares ACD1E1 and BCD2E2 outward from △ ABC. Draw a straight line KH passing through point C and intersect with straight line AB at point H, so that ∠ AHK=∠ ACD1. Draw D1M ⊥ KH and D2N ⊥ KH, with points M and N. The number relationship between line segment D1M and line segment D2N is ___.

{{ input(6) }}

• Subscript typing: _, for example $D_1$typing D_1

7. Given that point (A (2, -3)) is symmetric about the (x) axis, the coordinates of point (A ') are {{ select(7) }}

• (-2, -3)

• (2, 3)

• (-2, 3)

• (3, -2)