Question

Evaluate the function f (x)  4 • 7x for x  1 and x = 2. Show your work. i got 4×7^(-1) f(-1) = -28

4×7^2 f(2)=196
but its wrong

Answer 1

type y our question again
what's that "box" for ?

Answer 2

. Evaluate the function f (x) = 4 • 7x for x = -1 and x = 2. Show your work.

Answer 3

okay first replace x by -1 whatdo you get ?

Answer 4

4×7^(-1) i get this

Answer 5

is it \[\huge\rm f(x) = 4 \times 7^x\] ?

Answer 6

yes

Answer 7

ohh okay remember exponent rule \[\huge\rm x^{-m} = \frac{ 1 }{ x^m }\]

Answer 8

okay, so do i still replace the x with -1 or do i somehow have to make it a positive 1

Answer 9

she meant \(\bf a^{-{\color{red} n}} \implies \cfrac{1}{a^{\color{red} n}}\qquad \qquad

\cfrac{1}{a^{\color{red} n}}\implies a^{-{\color{red} n}}
\\ \quad \\
% negative exponential denominator
a^{{\color{red} n}} \implies \cfrac{1}{a^{-\color{red} n}}
\qquad \qquad

\cfrac{1}{a^{-\color{red} n}}\implies \cfrac{1}{\frac{1}{a^{\color{red} n}}}\implies a^{{\color{red} n}} \)

so..... yes

Answer 10

would the answer be 21 or -28

Answer 11

x is base and m is exponent
when there is negative exponent you should change that it's reciprocal

Answer 12

to*

Answer 13

21 how
7^(-1) = ???

Answer 14

\(\bf \large {
f(x)=4\cdot 7^x\qquad
\begin{cases}
x=-1\\
x=2
\end{cases}
\\ \quad \\
4\cdot 7^{{\color{red}{ -1}}}\implies 4\cdot \cfrac{1}{7^{\color{red}{ 1}}}\qquad and\qquad 4\cdot 7^{{\color{red}{ 2}}}
}\)