Identify coefficients: Identify the coefficients a, b, and c in the quadratic expression f2−20f+19. The quadratic expression is in the form af2+bf+c, where a=1, b=−20, and c=19.
Find numbers for ac: Find two numbers that multiply to give ac (which is 19, since a=1) and add up to b (which is −20).The numbers that satisfy these conditions are −1 and −19 because:−1×−19=19−1+(−19)=−20
Write quadratic expression: Write the quadratic expression using the two numbers found in the previous step to split the middle term. The expression becomes f2−f−19f+19.
Factor by grouping: Factor by grouping. Group the first two terms together and the last two terms together. f2−f + −19f+19
Factor out common factor: Factor out the greatest common factor from each group.f(f−1)−19(f−1)
Factor out common factor: Factor out the greatest common factor from each group.f(f−1)−19(f−1)Since both groups contain the common factor (f−1), factor this out.The factored form is (f−1)(f−19).