Answer:
[tex]b = 5 \sqrt{3} \ or\ b = -5 \sqrt{3}[/tex]
Step-by-step explanation:
Given
[tex]f(b) = b^2 - 75[/tex]
Required
Determine the roots
To get the root of the function, then f(b) must be 0;
i.e. f(b) = 0
So, the expression becomes
[tex]0 = b^2 - 75[/tex]
Add 75 to both sides
[tex]75 + 0 = b^2 - 75 + 75[/tex]
[tex]75 = b^2[/tex]
Take square roots of both sides
[tex]\sqrt{75} = \sqrt{b^2}[/tex]
[tex]\sqrt{75} = b[/tex]
Reorder
[tex]b = \sqrt{75}[/tex]
Expand 75 as a product of 25 and 3
[tex]b = \sqrt{25*3}[/tex]
Split the expression
[tex]b = \sqrt{25} *\sqrt{3}[/tex]
[tex]b = \±5 *\sqrt{3}[/tex]
[tex]b = \±5 \sqrt{3}[/tex]
[tex]b = 5 \sqrt{3} \ or\ b = -5 \sqrt{3}[/tex]
The options are not clear enough; however the roots of the equation are [tex]b = 5 \sqrt{3} \ or\ b = -5 \sqrt{3}[/tex]