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kx^(2)+5x=-7
In the given equation, 
k is a constant. Which of the following represents all values of 
k for which the equation has two distinct real solutions?
Choose 1 answer:
(A) 
k < -(25)/(28)
(B) 
k > -(25)/(28) and 
k!=0
(c) 
k < (25)/(28) and 
k!=0
(D) 
k > (25)/(28)

kx2+5x=7 k x^{2}+5 x=-7 \newlineIn the given equation, k k is a constant. Which of the following represents all values of k k for which the equation has two distinct real solutions?\newlineChoose 11 answer:\newline(A) k<-\frac{25}{28} \newline(B) k>-\frac{25}{28} and k0 k \neq 0 \newline(C) k<\frac{25}{28} and k0 k \neq 0 \newline(D) k>\frac{25}{28}

Full solution

Q. kx2+5x=7 k x^{2}+5 x=-7 \newlineIn the given equation, k k is a constant. Which of the following represents all values of k k for which the equation has two distinct real solutions?\newlineChoose 11 answer:\newline(A) k<2528 k<-\frac{25}{28} \newline(B) k>2528 k>-\frac{25}{28} and k0 k \neq 0 \newline(C) k<2528 k<\frac{25}{28} and k0 k \neq 0 \newline(D) k>2528 k>\frac{25}{28}
  1. Determine Conditions: We need to determine the conditions under which the quadratic equation kx2+5x+7=0kx^2 + 5x + 7 = 0 has two distinct real solutions. This depends on the discriminant, which is given by the formula D=b24acD = b^2 - 4ac, where aa, bb, and cc are the coefficients of x2x^2, xx, and the constant term, respectively.
  2. Calculate Discriminant: For the equation kx2+5x+7=0kx^2 + 5x + 7 = 0, a=ka = k, b=5b = 5, and c=7c = 7. Let's calculate the discriminant DD.\newlineD=b24ac=(5)24(k)(7)=2528kD = b^2 - 4ac = (5)^2 - 4(k)(7) = 25 - 28k.
  3. Discriminant Greater Than Zero: For the equation to have two distinct real solutions, the discriminant must be greater than zero. Therefore, we need D > 0.25 - 28k > 0.
  4. Solve Inequality for k: Solving the inequality for k, we get:\newline-28k > -25\newlinek < \frac{25}{28}.
  5. Consider Exclusion of k=0k=0: However, we must also remember that kk cannot be zero because if k=0k = 0, the equation becomes linear, not quadratic. Therefore, kk must also be different from zero.
  6. Combine Conditions: Combining the conditions, we find that kk must be less than 2528\frac{25}{28} and not equal to zero for the equation to have two distinct real solutions.

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