exam Maths Puzzle Numerical Ability

For all r = +/- 2, r squared-5r+6= r squared-4

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exam Other Question

I really am having a hard time with this problem. the 2x in the middle confuses me.
-4x is less than or equal to 2x<18 What is the solution for:

X4 + 11X2 - 80

and

2a2 - 11a + 12