How do you solve \x ^ { 2} - 8x = 20?
2 Answers
Explanation:
Re-arrange to form a standard quadratic form
Find the factors of
where sum of factors =
and rearrange in the equation.
Setting each factor equal to
Jun 2, 2017
Explanation:
"rearrange and equate to zero"
rArrx^2-8x-20=0
"factorise by 'splitting' the middle term"
rArrx^2+2x-10x-20=0larr" 2x - 10x = -8x"
"take out a common factor from each 'pair' of terms"
rArrcolor(red)(x)(x+2)color(red)(-10)(x+2)=0
"take out the common factor of " (x+2)
rArr(x+2)(color(red)(x-10))=0
"equate each factor to zero and solve"
x+2=0rArrx=-2larr" solution"
x-10=0rArrx=10larr" solution"