If 2x2+13x-7=0 then x could be equal to which of the following
1 answer:
Answer:
x = - 7, x =
Step-by-step explanation:
Given
2x² + 13x - 7 = 0
Consider the factors of the product of the coefficient of the x² term and the constant term which sum to give the coefficient of the x- term.
product = 2 × - 7 = - 14 and sum = + 13
The factors are + 14 and - 1
Use these factors to split the x- term
2x² + 14x - x - 7 = 0 ( factor the first/second and third/fourth terms )
2x(x + 7) - 1(x + 7) = 0 ← factor out (x + 7) from each term
(x + 7)(2x - 1) = 0
Equate each factor to zero and solve for x
x + 7 = 0 ⇒ x = - 7
2x - 1 = 0 ⇒ 2x = 1 ⇒ x =
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Answer:
Sarah is 13 years old
Step-by-step explanation:
Represent Sarah's age with S
Her first brother's age with F
Her second brother's age with B
So, we have:
From the first statement, we have:
---- (1)
From the second, we have:
---- (2)
The product of their ages is 40.
First, we make F the subject in (1) and B the subject in (2)
Their product is represented as follows:
Substitute values for F and B
Open bracket
Subtract 40 from both sides
Factorize:
Split:
or
But Sarah's age can't be 0 because she has two younger brothers.
So, we stick to
Make S the subject
<em>Hence, Sarah is 13 years old</em>