Pls answer for free 3 brainliests
2 answers:
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Answer:
1)
2)0
Step-by-step explanation:
for part 1:
Given cos(x) - cos^3(x)
= cos(x) (1- cos^2(x))
Using the identity
= cos(x)sin^2(x)
for part 2:
given
=
Using the identity cos(a)cos(b) + sin(a)sin(b)= cos(a-b)
=
=
=
=0!
Answer:
-5 ; 1/2
Step-by-step explanation:
<u>GIVEN :-</u>
- A quadratic polynomial f(x) = 2x² + 9x - 5
<u>TO FIND :-</u>
- Zeroes of f(x) = 2x² + 9x - 5
<u>GENERAL CONCEPTS TO BE USED IN THIS QUESTION :-</u>
Lets say there's a quadratic polynomial f(x) = ax² + bx + c , whose factors are (x - α) & (x - β). To find the values of x for which f(x) will be zero , equate the factors of f(x) with 0.
⇒ (x - α) = 0 & (x - β) = 0
⇒ x = α & x = β
Hence, it can be concluded that if (x - α) & (x - β) are factors of f(x) , then α & β are the roots of f(x).
<u>SOLUTION :-</u>
Factorise f(x) = 2x² + 9x - 5.
- Split its middle term.
- Take '2x' common from first two terms & '-1' from last two terms.
- Take (x + 5) common from the whole expression.
So , the factors of f(x) are (x + 5) & (2x - 1). Now equate the factors with zero.
⇒ (x + 5) = 0 & (2x - 1) = 0
⇒ x = -5 & x = 1/2
∴ The zeroes of f(x) = 2x² + 9x - 5 are (-5) & (1/2)
<u>VERIFICATION :-</u>
1) Put x = -5 in f(x) = 2x² + 9x - 5
⇒ f(-5) = 2(-5)² + 9×(-5) - 5
= 50 - 45 - 5
= 50 - 50
= 0
2) Put x = 1/2 in f(x) = 2x² + 9x - 5