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Mathematics 8 Online
OpenStudy (anonymous):

Part 1: Solve each of the quadratic equations below and describe what the solution(s) represent to the graph of each. Show your work to receive full credit. y = x2 + 3x + 2 y = x2 + 2x + 1 Part 2: Using complete sentences, answer the following questions about the two quadratic equations above. Do the two quadratic equations have anything in common? If so, what? What makes y = x2 + 3x + 2 different from y = x2 + 2x + 1?

OpenStudy (dumbcow):

i guess i should ask, have you learned factoring yet?

OpenStudy (anonymous):

Yes, but I am realllyy bad at it :/

OpenStudy (dumbcow):

ok that easiest way to solve these quadratic equations lets look at 1st one: \[x^{2} + 3x + 2 = 0\] we want to factor it so it looks like this \[(x+a)(x+b) = 0\] so \[a*b = 2\] \[a+b = 3\] what 2 numbers will work?

OpenStudy (anonymous):

Hmm..6?

OpenStudy (dumbcow):

what is 6? 2 numbers that multiply to 2 and add to get 3

OpenStudy (anonymous):

Ohhh, 1 and 2?

OpenStudy (dumbcow):

yep (x+1)(x+2) = 0 x = -1 and x = -2

OpenStudy (dumbcow):

lets do the 2nd one \[x^{2} +2x+1 = 0\] 2 numbers that multiply to 1 and add to get 2

OpenStudy (anonymous):

Why did you make them -1 and -2?

OpenStudy (dumbcow):

oh sorry, the 2 numbers we came up with 1 and 2 are used to factor the equation. but we still have to solve for "x" --> (x+1)(x+2) = 0 anything times 0 is 0 right so you can take each factor and set it equal to zero to find "x" --> x+1 = 0 --> x = -1 --> x+2 = 0 --> x = -2 these are the x-intercepts on the graph

OpenStudy (anonymous):

Oh ok, and for the second one would it be 1 and 1?

OpenStudy (dumbcow):

yes (x+1)(x+1) = 0

OpenStudy (anonymous):

Okay

OpenStudy (dumbcow):

here are the graphs |dw:1370378725271:dw|

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