Question

If k(x)=5x-6, which expression is equivalent to (k+k)(4)

Answer 1

Answer: (k+k)(4)=28

Step-by-step explanation:

(k+k) (4) means the same as adding k(4) and k(4). Since we are given k(x), we can use it to solve. There are two ways to solve. One is to find k(4), and then add them. Another way is to do (k+k)(x), then plug in x=4. I will show both methods.

Method 1

k(4)=5(4)-6                  [multiply]

k(4)=20-6                    [subtract]

k(4)=14                    

(k+k)(4)=14+14            [add k(4) and k(4)]

(k+k)(4)=28

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Method 2

(k+k)(x)=5x-6+5x-6     [combine like terms]

(k+k)(x)=10x-12

(k+k)(4)=10(4)-12         [plug in x=4, multiply]

(k+k)(4)=40-12             [subtract]

(k+k)(4)=28

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Now, we know that (k+k)(4)=28. We confirmed this with both methods.