#help pls inequalities work

28 messages · Page 1 of 1 (latest)

split lily
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HELP HOW DO I DO ALL OF THESE

umbral granite
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so, first factorise the quadratic, to get (x+3)(x+2). so (x+2) is the length of one side and (x+3) is the length of the other

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and then make the area they gave u in terms of x equal to the actual area

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so

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x^2+5x+6=42

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then we wanna factorise so we can get x

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so subtract 42 to make the whole thing equal to 0

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so x^2+5x-36=0

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factorise

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what adds to give 5 and multiplies to give -36

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9 and -4

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so

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(x+9)(x-4)

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so rn we have two possible values of x

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x=-9 and x=4

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cant be -9 as it will give a negative length, which isnt possible

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so has to be 4

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and that is question 6 finished

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now for question 7

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y=x^2+3x-4

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first

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lets figure out what we need to find to plot it

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1.y-intercept

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  1. roots(x intercept)
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  1. turning point
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  1. getting the y intercept is easy, its just the term with no x coefficient, so in this case it is -4
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  1. we should factorise to get the roots, what adds to give 3 and multiplies to give -4....4 and -1.
    so to factorise it we write it as (x+4)(x-1), which means our roots are x=-4 and x=1
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  1. you have to complete the square to find the turning point/ minimum.