High School

Given: [tex]f(x) = 3x^2 + 2x - 1[/tex]

What is the value of [tex]f(5)[/tex]?

A. 39
B. 84
C. 234
D. 624

Answer :

We are given the function

[tex]$$
f(x)=3x^2+2x-1.
$$[/tex]

We need to find the value of [tex]$f(5)$[/tex] by substituting [tex]$x=5$[/tex] into the function.

Step 1: Substitute [tex]$x=5$[/tex] into the function:

[tex]$$
f(5)=3(5)^2+2(5)-1.
$$[/tex]

Step 2: Compute [tex]$(5)^2$[/tex]:

[tex]$$
(5)^2=25.
$$[/tex]

Step 3: Multiply by 3:

[tex]$$
3(25)=75.
$$[/tex]

Step 4: Multiply 2 by 5:

[tex]$$
2(5)=10.
$$[/tex]

Step 5: Combine the results:

[tex]$$
f(5)=75+10-1.
$$[/tex]

Step 6: Calculate the final value:

[tex]$$
75+10=85,
$$[/tex]

[tex]$$
85-1=84.
$$[/tex]

Thus, the value of [tex]$f(5)$[/tex] is [tex]$\boxed{84}$[/tex], which corresponds to option B.