Factorise fully 1) \( 2 x^{2}+x-3 \) 2) \( 2 x^{2}+5 x-3 \) 3) \( 2 x^{2}-22 x+20 \) 4) \( 4 x^{2}+10 x-6 \)
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The Deep Dive
Let's factorise each of the given quadratic expressions step by step! 1) For \( 2x^{2}+x-3 \), we can use the method of splitting the middle term. We find two numbers that multiply to \( 2 \cdot -3 = -6 \) and add up to \( 1 \). These numbers are \( 3 \) and \( -2 \). We rewrite the expression as \( 2x^2 + 3x - 2x - 3 \), and then factor by grouping to get: \[ (2x - 3)(x + 1) \] 2) For \( 2x^{2}+5x-3 \), we again look for two numbers that multiply to \( -6 \) (from \( 2 \cdot -3 \)) and add to \( 5 \). The numbers \( 6 \) and \( -1 \) work. So we rewrite it as \( 2x^2 + 6x - 1x - 3 \) and factor by grouping: \[ (2x - 1)(x + 3) \] 3) In \( 2x^{2}-22x+20 \), notice we can first factor out a \( 2 \): \[ 2(x^{2}-11x+10) \] Now, we need to factor \( x^{2}-11x+10 \). Finding numbers that multiply to \( 10 \) and add to \( -11 \), we get \( -1 \) and \( -10 \): \[ x^2 - 11x + 10 = (x - 1)(x - 10) \] So the complete factorisation is: \[ 2(x-1)(x-10) \] 4) Finally, for \( 4x^{2}+10x-6 \), we can first factor out a \( 2 \): \[ 2(2x^2 + 5x - 3) \] Next, we factor \( 2x^2 + 5x - 3 \) in the same way as before. The numbers \( 6 \) and \( -1 \) work again allowing us to rewrite it as: \[ 2(2x - 1)(x + 3) \] So the fully factorised forms of the expressions are: 1) \( (2x - 3)(x + 1) \) 2) \( (2x - 1)(x + 3) \) 3) \( 2(x - 1)(x - 10) \) 4) \( 2(2x - 1)(x + 3) \)