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Let's have a look at a pair of brackets: (a+b)(c+d)To expand these brackets each value in one bracket must be multiplied by all values in the other bracket separately then added together. So we have: ac+a...

Because if we simply expand (x+y)² we'd get x²+y²+2xy which shows that there's an extra term which is 2xy. another practical way to check your work and see why LHS ≠ RHS i...

If I have a reocurring decimal I use a special trick to work it out as a fraction. The trick is to try and cancel out the reocurring bit by multiplying by 10 several times and then using subtractio...

Multiples that equal 20: 1 and 20, 2 and 10, 4 and 5Which of these multiples add/subtract to give -9?= -4 and -5Therefore answer is:(x-4)(x-5)=0x= 4 or x= 5

Drawing a diagram for this would show that the height of the tree above us is given by tan(63)*15, so the total height is this added to 1.6 m. This gives a height of 31 m.