answer: 8x^5y^7
explanation: you would multiply the constants; in this case it is 4 and 2 which gives you 8. When multiplying exponents you would add the exponents together and keep the variable (in this case you keep x where it is and you keep y where it is, the only that would change is the exponent). x^2 and x^3 gives you x^5. y^3 and y^4 gives you y^7.