#help pls inequalities work
28 messages · Page 1 of 1 (latest)
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
and then make the area they gave u in terms of x equal to the actual area
so
x^2+5x+6=42
then we wanna factorise so we can get x
so subtract 42 to make the whole thing equal to 0
so x^2+5x-36=0
factorise
what adds to give 5 and multiplies to give -36
9 and -4
so
(x+9)(x-4)
so rn we have two possible values of x
x=-9 and x=4
cant be -9 as it will give a negative length, which isnt possible
so has to be 4
and that is question 6 finished
now for question 7
y=x^2+3x-4
first
lets figure out what we need to find to plot it
1.y-intercept
- roots(x intercept)
- turning point
- getting the y intercept is easy, its just the term with no x coefficient, so in this case it is -4
- 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
- you have to complete the square to find the turning point/ minimum.