Math  /  Algebra

QuestionFind the difference quotient f(x+h)f(x)h\frac{f(x+h)-f(x)}{h}, where h0h \neq 0, f(x)=8x2f(x)=8 x-2
Simplify your answer as much as possible. f(x+h)f(x)h=\frac{f(x+h)-f(x)}{h}=

Studdy Solution

STEP 1

What is this asking? We're finding how much the function f(x)f(x) changes on average over a small interval of size hh. Watch out! Don't forget to distribute the negative sign correctly when subtracting f(x)f(x)!

STEP 2

1. Substitute the function
2. Expand and simplify

STEP 3

Alright, let's **kick things off** by substituting the expression for f(x+h)f(x+h) into our difference quotient formula!
Remember, f(x)=8x2f(x) = 8x - 2, so f(x+h)=8(x+h)2f(x+h) = 8(x+h) - 2.
So we get: f(x+h)f(x)h=8(x+h)2f(x)h \frac{f(x+h) - f(x)}{h} = \frac{8(x+h) - 2 - f(x)}{h}

STEP 4

Now, let's **plug in** our expression for f(x)f(x), which is 8x28x - 2: 8(x+h)2(8x2)h \frac{8(x+h) - 2 - (8x - 2)}{h} Notice those parentheses around 8x28x - 2!
They're super important because we're subtracting the *entire* function f(x)f(x).

STEP 5

Let's **distribute** that 8 in the numerator: 8x+8h2(8x2)h \frac{8x + 8h - 2 - (8x - 2)}{h} Now, **distribute** the negative sign: 8x+8h28x+2h \frac{8x + 8h - 2 - 8x + 2}{h} Look closely!
We have 8x8x and 8x-8x, and 2-2 and +2+2.
These will add to zero, which simplifies things nicely: 8hh \frac{8h}{h}

STEP 6

Since h0h \neq 0, we can **divide** the numerator and denominator by hh, which is the same as multiplying by 1h\frac{1}{h} in the numerator and 1h\frac{1}{h} in the denominator: 8hh=8h1h=8h1h1h1h=8111=8 \frac{8h}{h} = \frac{8h}{1 \cdot h} = \frac{8h \cdot \frac{1}{h}}{1 \cdot h \cdot \frac{1}{h}} = \frac{8 \cdot 1}{1 \cdot 1} = 8 So, our **final simplified expression** is 88!

STEP 7

f(x+h)f(x)h=8\frac{f(x+h)-f(x)}{h}=8

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