Two numbers have a difference of 15 and a product of 199.75.The larger of the two numbers is x.(a) Show thatx2 – 15x – 199.75 = 0(3)(b) Solve the equationx2 – 15x – 199.75 = 0X2是 X的2次方

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Twonumbershaveadifferenceof15andaproductof199.75.Thelargerofthetwonumbersisx.(a)Showthatx2–15x–199.7

Two numbers have a difference of 15 and a product of 199.75.The larger of the two numbers is x.(a) Show thatx2 – 15x – 199.75 = 0(3)(b) Solve the equationx2 – 15x – 199.75 = 0X2是 X的2次方
Two numbers have a difference of 15 and a product of 199.75.
The larger of the two numbers is x.
(a) Show that
x2 – 15x – 199.75 = 0
(3)
(b) Solve the equation
x2 – 15x – 199.75 = 0
X2是 X的2次方

Two numbers have a difference of 15 and a product of 199.75.The larger of the two numbers is x.(a) Show thatx2 – 15x – 199.75 = 0(3)(b) Solve the equationx2 – 15x – 199.75 = 0X2是 X的2次方
Since X is larger,X-15 is the smaller No.Therefore,199.75=x*(x-15)
a)LHS=x2-15x-x·(x-15)
=0
=RHS
b)x=-8.5 or23.5

(a)suppose another number is y,
then x-y=15
xy=199.75
therefore,x^2-15x-199.75=0 => x^2-(x-y)x-xy=0
simplify x^2-x^2+xy-xy=0
(b)Use x=(-b+(-)sqrt(delta))/2a
x^2-15x-199.75=o
-b=15
delta=1024
therefore, x1=23.5 x2=-8.5

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