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
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"#