Answer:
[tex]\boxed{\sf \ \ \ answer \ b. \ \ +5 \ \ \ }[/tex]
Step-by-step explanation:
Hello
let's assume that we are looking for x >=0
[tex]4x^2=100 <=> \dfrac{4x^2}{4}=x^2=\dfrac{100}{4}=25\\<=>\sqrt{x^2}=25\\<=> |x| = 5 <=> x = 5 \ or \ x=-5[/tex]
Let's assume that we are looking for x>=0
so the correct answer is 5