Question
Given that 2x^2-kx+18 is a perfect square,find k and hence solve the equation 2x^2-kx+18=0 by factorisation.Plz explain in detail.
Answers
R_scott
the 2nd order (squared) term must have a coefficient of one
dividing by 2 ... x^2 - k/2 x + 9 = 0
... take the square root of the constant term ... √9 = ± 3
factoring ... (x - 3)^2 = x^2 - 6 x + 9 ... k/2 = 6 ... k = 12
dividing by 2 ... x^2 - k/2 x + 9 = 0
... take the square root of the constant term ... √9 = ± 3
factoring ... (x - 3)^2 = x^2 - 6 x + 9 ... k/2 = 6 ... k = 12
lucy
Why must it have a coefficient of one
R_scott
must is probably to strong an imperative
... it makes the calculations less "messy"
... it makes the calculations less "messy"