Answer:
The option 'b' is correct.
Step-by-step explanation:
Given the function
[tex]f\left(x\right)\:=\:10x^2\:+\:40x\:+\:42[/tex]
Determining the y-intercept
The y-intercept can be obtained by setting the value x = 0
[tex]y\:=\:10x^2\:+\:40x\:+\:42[/tex]
[tex]y\:=\:10\left(0\right)^2\:+\:40\left(0\right)\:+\:42[/tex]
[tex]= 0+0+42[/tex]
[tex]=42[/tex]
Therefore, the y-intercept is:
Determining the axis of symmetry
Given the equation
[tex]y=\:10x^2\:+\:40x\:+\:42[/tex]
For a parabola in standard form [tex]y=ax^2\:+\:bx\:+c[/tex]
the axis of symmetry is the vertical line that goes through the vertex
[tex]x=\frac{-b}{2a}[/tex]
so
The axis of symmetry for [tex]y=ax^2\:+\:bx\:+c[/tex] is [tex]x=\frac{-b}{2a}[/tex]
[tex]a=10,\:b=40[/tex]
[tex]x=\frac{-b}{2a}[/tex]
[tex]x=\frac{-40}{2\cdot \:10}[/tex]
[tex]x=-2[/tex]
Therefore, the option 'b' is correct.
