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2x + y = 10 (1) 3x + 4y = 25 (2) 1. Eliminate y. Method 1: (1) x 4: 8x + 4y = 40 (1') (1') - (2): 5x = 15 Method 2: Rearrange (1): y = 10 - 2x (1") Substitute (1") into (2): 3x + 4(10 - 2x) = 25 (3...

If you're asked to solve a quadratic equation, you could factorise it, or you could use the quadratic formula. The quickest way is to factorise, but sometimes the numbers are too tricky to factorise, (if an ...

German spelling can be tricky to get to grips with when you first start learning, but there's a simple trick to remembering whether the word you're writing is 'ei' (e.g. 'bleiben') or 'ie' (e.g. 'spielen'). ...

The rule for this is simple, although can be somewhat confusing when you first start learning German! The rule is: if there's movement from one place to another, use 'sein'. If there's not, use 'haben' . Exa...

Osmosis is the movement of water molecules from an area of high water concentration to an area of low water concentration through a partially/selectively permeable membrane (PPM) . It occurs because of conce...