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On a piece of paper graph f(x)=5•(0.4)^x

Your client has saved $1,860 for a down payment on a house. a government loan program requires a down payment equal to 3% of the loan amount. what is the largest loan amount that your client could receive with this program

Write a polynomial function f of least degree that has rational coefficients, a leading coefficient of 1, and the given zeros. 3, 4+2i, 1+(sqrt)7 the answer is supposed to be: f(x)=x(^5)-13x(^4)+60x(^3)-82x(^2)-144x+360 what am i doing wrong?