Evaluate this expression when a = 3, b = 4, c = 6 : ab-c
2 answers:
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Answer:
x = 5
Step-by-step explanation:
The area (A) of a triangle is calculated as
A = bh ( b is the base and h is height )
Here A = 20, b = (x + 3) and h = (2x - 5) , then
(x + 3)(2x - 5) = 20 ← multiply both sides by 2
(x + 3)(2x - 5) = 40 ← expand left side using FOIL
2x² + x - 15 = 40 ( subtract 40 from both sides )
2x² + x - 55 = 0 ← in standard form
(x - 5)(2x + 11) = 0 ← in factored form
Equate each factor to zero and solve for x
x - 5 = 0 ⇒ x = 5
2x + 11 = 0 ⇒ 2x = - 11 ⇒ x = - 5.5
But x > 0 , so x = 5
Answer:
The ball will be at 100 feet at time x=0.5 sec and at time x=7.5 sec
Step-by-step explanation:
<u><em>The correct question is</em></u>
A ball is launched upward from a height 40 feet above ground level. the ball's height at t seconds is given by h(t)=-16t^2+128t+40 At what time(s) will the ball be at 100 feet?
we have
so
For h(t)=100 ft
substitute in the equation and solve for x
The formula to solve a quadratic equation of the form
is equal to
in this problem we have
so
substitute in the formula
therefore
The ball will be at 100 feet at time x=0.5 sec and at time x=7.5 sec