a, \(f\left(x\right)+g\left(x\right)+h\left(x\right)=2x^2+5+3x^2+2x+4+x^2-4=6x^2+2x+5\)
b, \(f\left(x\right)-g\left(x\right)+h\left(x\right)=2x^2+5-3x^2-2x-4+x^2-4=-2x-3\)
a, f(x) + g(x) + g(x) = (2x2 + 5) + (3x2 + 2x + 4) + (3x2 + 2x + 4)
= 2x2 + 5 + 3x2 + 2x + 4 + 3x2 + 2x + 4
= 2x2 + 3x2 + 3x2 + 5 + 4 + 4 + 2x + 2x
= ( 2 + 3 + 3 )x2 + ( 5 + 4 + 4 ) + ( 2 + 2 )x
= 8x2 + 13 + 4x
b, f(x) - g(x) + h(x) = ( 2x2 + 5 ) - ( 3x2 + 2x + 4 ) + ( x2 - 4 )
= 2x2 + 5 - 3x2 - 2x - 4 + x2 - 4
= 2x2 - 3x2 + x2 + 5 - 4 - 4 - 2x
= ( 2 - 3 + 1 )x2 + ( 5 - 4 - 4 ) - 2x
= -3 - 2x