(8x^(2)-4x-29)+(9x^(2)+7x)=
add up all the x^2 terms: 8x^2+9x^2 = 17x^2
add up all the x terms: -4x + 7x = 3x
add up all the constants: 29
answer: 17x^2 + 3x + 29
add up all the x terms: -4x + 7x = 3x
add up all the constants: 29
answer: 17x^2 + 3x + 29