Solve the equation x^2-9x+20=0
First, we need to factorise the equation on the left hand side, this can be done by finding two numbers that add together to make the 'b' coefficient (-9) and multiply to make the 'c' coefficient (20).
This will give -5 and -4. Therefore, (x-5)(x-4)=0. So, either (x-5)=0, or (x-4)=0 Giving x=5 or x=4 as the final answers.
JB
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How do you factorise a quadratic equation into the form (x+A)(x+B), for example x²+x-6 =0?
i) The point A on a graph is (6,-7), and point B is (3,5). Calculate the equation of the straight line that passes through both A and B. ii) Does the line pass through the point C (-2,26)?
Make 'a' the subject of the formula: p = (3a + 5) / (4 - a)