Percy solved the equation x2 + 7x + 12 = 12. His work is shown below. Is Percy correct? Explain.
2 answers:
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Answer:
Step-by-step explanation:
From the step given step 6
(b² — 4ac) / 4a² = (x + b/2a)²
Mistake in question it is (x + b/2a)²
Step 7 given
±√(b² —4ac) /2a = x + b/2a
Mistake in question it is over 2a and not 1a.
1. The step taken from step 6 to step 7 is taking square roots of both sides
(b² — 4ac) / 4a² = (x + b/2a)²
Taking square of both sodes
√(b²—4ac) / √4a² = √(x + b/2a)²
√(b²—4ac) / 2a = x + b/2a
This is the required step 7.
Now, subtracting b/2a from both sides
√(b²—4ac) / 2a - b/2a= x + b/2a -b/2a
√(b²—4ac) / 2a — b/2a = x
(√(b²—4ac) — b)/2a = x
x = [—b ± √(b²—4ac)] / 2a
So, this is the required formula method
The discriminant is D = b²—4ac.
