Question

if f(x)=x²-5x-36 and g(x)=x²+9x+20, then for what value of x is 2f(x)=3g(x)

Answer 1

For the value of x for which 2f(x) will be 3 times g(x) =

2(x²-5x-36) = 3(x²+9x+20)

=} 2x²-10x-72 = 3x²+27x+60

=} 0 = (3x²-2x²)+(27x+10x)+(60+72)

=} 0 = x²+37x+132

=} 0 = x²+33x+4x+132

=} 0 = x(x+33)+4(x+33)

=} 0 = (x+4)(x+33)

So , x=-4 or -33