I keep forgetting the process for this: 3(x^2 + 5)(x^2 - 5) Can someone help?

Mathematics

1 answer:

Snezhnost [94]3 years ago

5 0

Answer:

see explanation

Step-by-step explanation:

Note that (x² + 5)(x² - 5) are the factors of a difference of squares

a² - b² = (a + b)(a - b)

with a = x² and b = 5, hence

(x² + 5)(x² - 5) = (x²)² - 5² = $x^{4}$ - 25, thus

3( $x^{4}$ - 25) = 3 $x^{4}$ - 75

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Use a matrix to solve the system:

Romashka-Z-Leto [24]

Answer:

(2.83 , 1 , 4)

Step-by-step explanation:

$2x+2y-z=4\\4x-2y-2z=2\\3x+3y-4z=-4\\$

Rewrite these equations in matrix form

$\left[\begin{array}{ccc}2&2&-1\\4&-2&-2\\3&3&-4\end{array}\right] \left[\begin{array}{ccc}x\\y\\z\end{array}\right]=\left[\begin{array}{ccc}4\\2\\-4\end{array}\right] \\$

we can write it like this,

$AX=B\\X=A^{-1}B$

so to solve it we need to take the inverse of the 3 x 3 matrix A then multiply it by B.

We get the inverse of matrix A,

$A^{-1}=\left[\begin{array}{ccc}7/15&1/6&-1/5\\1/3&-1/6&0\\3/5&0&-2/5\end{array}\right] \\$

now multiply the matrix with B

$X=A^{-1}B\\\\\left[\begin{array}{ccc}x\\y\\z\end{array}\right] =\left[\begin{array}{ccc}7/15&1/6&-1/5\\1/3&-1/6&0\\3/5&0&-2/5\end{array}\right]\left[\begin{array}{ccc}4\\2\\-4\end{array}\right] \\\\\\\left[\begin{array}{ccc}x\\y\\z\end{array}\right] =\left[\begin{array}{ccc}2.83\\1\\4\end{array}\right] \\$