Question

Robin solved a quadratic equation using the process shown. Complete the explanation of her mistake.

Options:
a) It should be 4, because when Robin squared the value of b, she said that (-2)² = -2 * -2, The correct answer should be 4.
b) It should be 5, because when Robin squared the value of b, she said that (-2)² = -40530, The correct answer should be 5.
c) It should be 4, because when Robin squared the value of b, she said that (-2)² = 74-7, The correct answer should be 4.
d) It should be 5, because when Robin squared the value of b, she said that (-2)² = 21/11, The correct answer should be 5.

Answer 1

Robin made a mistake in squaring the coefficient 'b' while using the quadratic formula. The correct value when squaring -2 is 4, not a negative or different positive number.

Step-by-step explanation:

The student is asking about how to correctly apply the quadratic formula to solve a quadratic equation. Robin's mistake involves the squaring of the term 'b' in the formula. When squaring any number, including negative numbers, the result is always non-negative. Therefore, given that 'b' equals -2, when we square it (-2)², we should get 4 rather than any other incorrect value.

The correct option that completes the explanation of Robin's mistake is: It should be 4, because when Robin squared the value of b, she said that (-2)² = -2 * -2, The correct answer should be 4.

Applying the quadratic formula correctly is crucial in finding the solution to a quadratic equation, and it's important to remember to square the coefficients accurately.