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I need to know the new equation, I’ve provided a picture

I need to know the new equation, I’ve provided a picture-example-1
User Glenis
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1 Answer

15 votes
15 votes

Hello there. To solve this question, we'll simply have to make x => x + 5 in the function.

Given the function:


f(x)=4x^2-3^{}

We have to determine f(x + 5)

By making x => x + 5 in this function, we get:


f(x+5)=4\cdot(x+5)^2-3

Now remember the binomial expansion of order 2:


(a+b)^2=a^2+2ab+b^2

Therefore we have:


f(x+5)=4\cdot(x^2+2\cdot x\cdot5+5^2)-3

Multiply the terms inside parentheses and calculate the square.


f(x+5)=4\cdot(x^2_{}+10x+25)-3

Apply the distributive property


f(x+5)=4x^2+4\cdot10x+4\cdot25-3

Multiply and add the numbers


\begin{gathered} f(x+5)=4x^2+40x+100-3 \\ \boxed{f(x+5)=4x^2+40x+97} \end{gathered}

This is the answer we're looking for.

A way of showing this is the correct answer is to make x = 1 and x = 6 in the former function:


\begin{gathered} f(1)=4\cdot1^2-3=4\cdot1-3=4-3=1 \\ f(6)=4\cdot6^2-3=4\cdot36-3=144-3=141 \end{gathered}

Then making x = 1 in the expression we found after:


f(1+5)=f(6)=4\cdot1^2+40\cdot1+97=4+40+97=141

As expected.

User Rich Hoffman
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3.0k points