Hints, Tips and Tricks.
ALGEBRA
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v
To
calculate the GRADIENT of a straight line graph, you need to draw in a sort of
(backwards) L
shape
to
help work out the (change in y) and the (change in x). Then you divide.
Example : P(2,3) Q(6,11)
Gradient = change in y = 11-3 = 8 = 2
change in x 6-2 4
[ RP Y9 Alsop ]
v In the equation y=mx+c, the constant [c] is the y-axis intercept value (x=0) so you can see where the graph crosses the y-axis.
Example : y=4x+3 would cross the y-axis at (0,3)
[ MM Y9 Croxteth ]
v With LINEAR equations [y=mx+c], the number [m] in front of the x tells you the GRADIENT of the straight line graph.
Example : y=3x + 2 has a gradient of 3
[ LH - Y9
Croxteth ]
v If Linear Equations have the same gradient [m], they will have parallel straight line graphs.
Example : y=2x will be parallel to y=2x+1 and y=2x-3 etc.
[ JM Y9 Croxteth ]
v If 2 straight line graphs (linear) have different gradients, they will cross (intersection point) somewhere.
Example : y=3x+1 will intersect y= -2x+6 at (1,4)
[ JH Y9 Croxteth ]
v For 2 graphs, you can find out the co-ordinates (x,y) of an intersection point by solving the 2 simultaneous equations
Example : x+y=19
x-y=5.
Add to ELIMINATE y. Then 2x=24, x=12, so y=7 Intersection at (12,7)
[ RK Y10 De La Salle ]
v
When you are FACTORISING a QUADRATIC equation,
make sure it is like this x2+bx+c,
then the number [c] on the end tells you what the two number factors will multiply to make (check + and -).
Example : x2+5x-36 Try (+9)x(-4) = -36 , (+6)x(-6)=-36 ,
(+12)x(-3)=-36 etc
[ AH Y9 Anfield ]
v When you are trying to check the factors of a quadratic equation, the middle number [b] (co-efficient of x) tells you
what the two number factors will total (be careful with the + and -).
Example : x2+5x-36 = (x+9)(x-4) Check (+9)x(-4) = -36 and (+9 4) = +5 yes !
[ JR Y9 Anfield ]
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