Q. Which of the equations are true identities?A. (x−2y)2=x2−4xy+4y2B. (m+1)2−m2=1Choose 1 answer:(A) Only A(B) Only B(C) Both A and B(D) Neither A nor B
Analyze option A: Let's first analyze option A: (x−2y)2=x2−4xy+4y2We will use the formula (a−b)2=a2−2ab+b2 to expand the left side of the equation.
Expand (x−2y)2: Expanding (x−2y)2 using the formula:(x−2y)2=x2−2⋅(x)⋅(2y)+(2y)2=x2−4xy+4y2
Compare expanded form with right side: Now let's compare the expanded form with the right side of the equation given in option A:Expanded form: x2−4xy+4y2Given form: x2−4xy+4y2Since both forms are identical, option A is a true identity.
Analyze option B: Next, we analyze option B: (m+1)2−m2=1We will expand (m+1)2 and then subtract m2 to see if the result equals 1.
Expand (m+1)2 and subtract m2: Expanding (m+1)2 using the formula (a+b)2=a2+2ab+b2:(m+1)2=m2+2⋅m⋅1+12=m2+2m+1
Compare result with 1: Now we subtract m2 from both sides of the expanded form:(m2+2m+1)−m2=2m+1This does not equal 1, as the right side of the equation in option B suggests.
Compare result with 1: Now we subtract m2 from both sides of the expanded form:(m2+2m+1)−m2=2m+1This does not equal 1, as the right side of the equation in option B suggests. Since the result of the expansion and subtraction in option B does not equal 1, option B is not a true identity.
More problems from Compare linear and exponential growth