Who can solve this question?I will mark them as branlist.

Answer:
See below
Step-by-step explanation:
[tex] \overrightarrow a= \bigg(\frac{5}{\sqrt 34},\:\frac{3}{\sqrt 34}\bigg)[/tex]
We have to show that [tex] \overrightarrow a[/tex] is an unit vector.
To show this, we will find the modulus of [tex] \overrightarrow a[/tex] and if its value is 1, it will be a unit vector.
So,
[tex] | \overrightarrow a| = \sqrt{\bigg(\frac{5}{\sqrt 34} \bigg) ^{2}+\bigg(\frac{3}{\sqrt 34}\bigg)^{2} } \\ \\ | \overrightarrow a| = \sqrt{\frac{25}{ 34} +\frac{9}{ 34} } \\ \\ | \overrightarrow a| = \sqrt{\frac{25 + 9}{ 34} } \\ \\ | \overrightarrow a| = \sqrt{\frac{34}{ 34} } \\ \\ | \overrightarrow a| = \sqrt{1} \\ \\ | \overrightarrow a| = 1[/tex]
Thus, [tex] \overrightarrow a[/tex] is a unit vector.