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The FOIL technique (First, Outside, Inside, Last) is very useful when expanding out brackets. Using this method we have:2x * x = 2x² (First)2...

Sub y=x^2 - 5x + 4 into x+2y=19x+2(x^2 -5x + 4) = 19x + 2x^2 -10x + 8 =192x^2 - 9x -11 = 0 (2x -11)(x+1) = 0x= 5.5x=-1

Solve x²- 4x - 5 = 0
A very full explanation would be:
Start by listing the pairs of numbers that can be multiplied together to get 1 * -5 = -5 (i.e. the coefficient of the first ter...

Simultaneous equations:
x=y+1 y=2x+3
First solve for x. y=2x+3 so first equation becomes: x=(2x+3)+1 x-2x-3-1=0 -1x-4=0x+4=0 x=-4
Solve for y: y=2x+3 y=2(-4)+3 y=-8+3y=-5

There are three methods for solving simultaneous equations: elimination, substitution and by using graphs.Elimination is a good method in this case as the y terms are equal in both equations. We just add ...