Mathematics, 22.06.2019 13:20 joannegrace4898

Mathieu is finding the x-intercepts of the function f(x) = x2 + 4x + 3. his work is shown below . which error did mathieu make?

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Answer from: idcbrooo

I can't see Mathieu's work but I will show the right steps and maybe you can find where Mathieu went wrong.

f(x)=x^2+4x+3

f(x)=(x+3)(x+1) Since 3*1=3 and 3+1=4

The x-intercepts can be found by setting y to 0 and solving for x

(in other words replace that f(x) thing with 0 and solve for x)

0=(x+3)(x+1)

Now set both factors equal to 0

x+3=0 or x+1=0

x =-3 x=-1

The x-intercepts are at (-3,0) and (-1,0)

Answer from: Qwerty2771

he set the factored expressions equal to each other

Step-by-step explanation:

Answer from: ringo12384

Step-by-step explanation:

Answer from: earaceli222

He set the factored expressions equal to each other. instead of setting them equal to zero

Step-by-step explanation:

f(x) = x^2 + 4x + 3. His work is shown below.

0 = x^2 + 4x + 3

0 = (x + 3)(x + 1)

Here is where we use the zero product property

x+3 = 0 x+1 =0 We do not set them equal to each other

Answer from: mercymain1014

he set the factored expressions equal to each other.

Step-by-step explanation:

Answer from: michaellagann2020

He set the factored expressions equal to each other

Answer from: china236

He set the factored expressions equal to each other

Step-by-step explanation:

Answer from: jay4881

Step-by-step explanation:

He set the factored expressions equal to eachother

Answer from: Destinywall

The x-intercepts occur when the function is equal to zero. Graphically, this is when the graph touches the x-axis, hence "x-intercepts".

x^2+4x+3=0

You can solve this in three ways, factoring, "completing the square", or simply using the quadratic equation (which is the result of completing the square). You did not show Mathieu's work, so I'll complete the square, as it is conceptually very important. (because it is the derivation of the quadratic formula and because it is straight forward when factoring would be nearly impossible like it is in most real world problems...you rarely get simple integer factors outside of the classroom :))

x^2+4x+3=0 subtract 3 from both sides

x^2+4x=-3 halve the linear coefficient, square it, add that value to both sides, in this case, (4/2)^2=2^2=4, so add 4 to both sides

x^2+4x+4=1 now the left side is a perfect square...

(x+2)^2=1 take the square root of both sides

x+2= ±√1 subtract 2 from both sides

x=-2±1

x=-3 and -1

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Mathieu is finding the x-intercepts of the function f(x) = x2 + 4x + 3. his work is shown below . wh...