Question

number of real solution of the equation x²-9x+20=0

Answer 1

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.

please please mark as brilliant

Answer 2

$x ^{2} - 9x + 20 \\ x {}^{2} - 4x - 5x + 20 \\ x(x - 4) - 5(x - 4) \\ (x - 5)(x - 4) \\ x = 4 \: or \: x = 5$