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If the sum of two numbers is 50 and their difference is 10, what is the product of the numbers?
500
600
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600
Use the algebraic identity xy=4(x+y)2тИТ(xтИТy)2тАЛ to directly find the product without solving for individual numbers.
Sum of two numbers is 50 and their difference is 10.
xy=4(x+y)2тИТ(xтИТy)2тАЛ
Use the algebraic identity xy=4(x+y)2тИТ(xтИТy)2тАЛ to directly find the product without solving for individual numbers.
Students often waste time solving for both numbers individually by adding and subtracting equations instead of using the direct algebraic identity.
Define Equations
Let the two numbers be x and y. We are given that their sum is 50 and difference is 10.
x+y=50,xтИТy=10
Apply Algebraic Identity
We can find the product xy using the identity for the difference of squares or standard expansion of (x+y)2 and (xтИТy)2.
(x+y)2тИТ(xтИТy)2=4xy
Substitute Values
Substitute the given values of sum (50) and difference (10) into the equation.
502тИТ102=4xy
Calculate the Product
Simplify the squares and solve for xy.
2500тИТ100=4xyтЯ╣2400=4xyтЯ╣xy=600
B is correct because the product of the numbers calculated via the identity is 600.
Similar algebraic identities are frequently used in quadratic equations and number system problems in competitive exams.