Find the value of f(4) for the function

Mathematics

1 answer:

cluponka [151]2 years ago

8 0

Answer:

f(4) = 7

Step-by-step explanation:

The notation for these type of problems is very confusing. Just remember that f(x) is the same thing as y (or some variable). Even if there is a number or something on the inside of the parentheses, it's still just a variable.

In our case

f(a) = 2(a + 4) -9

could be rewritten as

y = 2(a + 4) - 9

the thing on the inside of the parentheses signifies what the equation is dependent on.

so when is says f(4), it just want's you to trade out a for a 4, but the equation is still the same.

f(4) = 2((4) + 4) - 9

Now, just follow the order of operations

f(4) = 2(8) - 9

f(4) = 16 - 9

f(4) = 7

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Find all the zeros of the equation x^4-6x^2-7x-6=0

rusak2 [61]

Answer:

The zeros are

$x=-2,\:x=3,\:x=-\frac{1}{2}+i\frac{\sqrt{3}}{2},\:x=-\frac{1}{2}-i\frac{\sqrt{3}}{2}$

Step-by-step explanation:

We have been given the equation x^4-6x^2-7x-6=0

Use rational root theorem, we have

$a_0=6,\:\quad a_n=1$

$\mathrm{The\:dividers\:of\:}a_0:\quad 1,\:2,\:3,\:6,\:\quad \mathrm{The\:dividers\:of\:}a_n:\quad 1$

$\mathrm{Therefore,\:check\:the\:following\:rational\:numbers:\quad }\pm \frac{1,\:2,\:3,\:6}{1}$

$-\frac{2}{1}\mathrm{\:is\:a\:root\:of\:the\:expression,\:so\:factor\:out\:}x+2$

$=\left(x+2\right)\frac{x^4-6x^2-7x-6}{x+2}\\$

$=x^3-2x^2-2x-3$

Again factor using the rational root test, we get

$=\left(x+2\right)\left(x-3\right)\left(x^2+x+1\right)$

Using the zero product rule, we have

$x+2=0:\quad x=-2\\x-3=0:\quad x=3\\x^2+x+1=0\\\\x_{1,\:2}=\frac{-1\pm \sqrt{1^2-4\cdot \:1\cdot \:1}}{2\cdot \:1}\\\\=-\frac{1}{2}+i\frac{\sqrt{3}}{2},\:x=-\frac{1}{2}-i\frac{\sqrt{3}}{2}$