Can some one tell me two numbers that multiply to -400 and add to 9. This is for some polynomials homework


P= -400
S= 9

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Originally Posted by schc7

Can some one tell me two numbers that multiply to -400 and add to 9. This is for some polynomials homework


P= -400
S= 9

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well lets make 2 equations.
let x,y be 2 numbers

x + y = 9
xy = -400

now solve for x and y by using substitution

Thanks, but that's not helping

well you need to know how to do the substitution method and you need to know how to factor to solve the 2 equations.

so you have
xy=-400
x+y = 9

lets isolate a variable so lets take equation 2 which is x + y = 9. lets isolate for x so you get
x = 9-y

now plug this value into your other equation xy = -400 so you get
(9-y)y = -400

now expand brackets so you get
9y - y^2 = -400

move everything to one side so you get
y^2-9y-400 = 0

now factor or use quadratic formula to solve for y. once you get y than you plug it back into original equation and you get x and those are your 2 numbers.

to check your answer the 2 numebrs are 25 and -16

Thanks man. Are you in grade ten too? Or are u just an adult that's good at math

I am in grade 12. I know this stuff like 2+2. once you get to grade 12 you would be looking back at this saying how easy it is.