Question

Joyce is trying to solve the equation y = x2 − 8x + 7 using the quadratic formula. She has made an error in one of the steps below. Find the step where Joyce went wrong.
Step 1: x equals negative 8 plus or minus the square root of the quantity eight squared minus four times one times seven, end quantity, all over two times one.

Step 2: x equals negative 8 plus or minus the square root of sixty-four minus twenty-eight all over two times one.

Step 3: x equals negative 8 plus or minus the square root of thirty-six all over two times one.

Step 4: x equals negative 8 plus or minus six all over two.

Step 1
Step 2
Step 3
Step 4

Answer 1

Joyce is trying to solve the equation y = x2 − 8x + 7 using the quadratic formula. She has made an error in one of the steps below. Find the step where Joyce went wrong. FIRST OF ALL, Y MUST EQUAL 0 Step 1: x equals negative 8 plus or minus the square root of the quantity eight squared minus four times one times seven, end quantity, all over two times one. THIS IS WRONG. IT SHOULD BE POSITIVE 8 plus or minus the square root of the quantity eight squared minus four times one times seven, end quantity, all over two times one. Step 2: x equals POSITIVE 8 plus or minus the square root of sixty-four minus twenty-eight all over two times one. Step 3: x equals POSITIVE 8 plus or minus the square root of thirty-six all over two times one. Step 4: x equals POSITIVE 8 plus or minus six all over two. Step 5 X=(8±6)/2 Step 6 X=14/2 =7 or Step 7 X=2/2 =1 Answers {1,7}. So the answer is Step 1.