How do you combine $(3 k + 4) (3 k - 5)$ $(3k + 4) ( 3k - 5)$ ?

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How do you combine $(3 k + 4) (3 k - 5)$ $(3k + 4) ( 3k - 5)$ ?

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Answer 1 · 2017-02-20T16:38:52

$9 k^{2} - 3 k - 20$ $9k^2-3k-20$

Explanation:

Each term in the second bracket must be multiplied by each term in the first bracket as shown below.

$(3 k + 4) (3 k - 5)$ $(color(red)(3k+4))(3k-5)$

$= 3 k (3 k - 5) + 4 (3 k - 5)$ $=color(red)(3k)(3k-5)color(red)(+4)(3k-5)$

distributing brackets gives.

$= 9 k^{2} - 15 k + 12 k - 20$ $=9k^2-15k+12k-20$

collect like terms.

$= 9 k^{2} - 3 k - 20$ $=9k^2-3k-20$

Answer 2 · 2017-02-20T17:56:10

$9 k^{2} - 3 k - 20$ $9k^2-3k-20$

Explanation:

$(3 k + 4) (3 k - 5)$ $(3k+4)(3k-5)$

$color(white)(........................)3k+4$
$color(white)(........................)ul(3k-5)$
$color(white)(........................)9k^2+12k$
$color(white)(..............................)ul(-15k-20$
$color(white)(.........................)ul(9k^2-3k-20)$

or

$(3k+4)(3k-5)$

$3k xx 3k=color(white)(.....)color(red)(9k^2)$

$4 xx 3k=color(white)(.......)color(red)(12k$

$-5 xx 3k=color(red)(-15k$

$4 xx -5=color(white)(.)-ulcolor(red)(20$

Add the answers together

$:.=color(red)(9k^2+12k-15k-20$

$:.=9k^2-3k-20$

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How do you combine $(3 k + 4) (3 k - 5)$ $(3k + 4) ( 3k - 5)$ ?

2 Answers

Explanation:

Explanation:

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