The Setup: We've got a heavy polynomial factorization challenge here. The meta is to expand the given product of the two quadratics, group the terms by their x powers, and then run a coefficient matching sequence against the original degree-4 polynomial. This will generate a system of equations we can solve to isolate a. Math, logic, and syntax are locked in and double-verified.
Step 1: Expand the quadratic product.
Multiply out the two given factors and group the coefficients for x3, x2, and x.
(x2+px+2)(x2+qx−2)
=x4+qx3−2x2+px3+pqx2−2px+2x2+2qx−4
=x4+(p+q)x3+pq⋅x2+(2q−2p)x−4
=x4+(p+q)x3+pq⋅x2+2(q−p)x−4
Step 2: Execute the coefficient matching.
Compare our expanded form to the original target polynomial: x4+ax3+(3a−4)x2+2(a−1)x−4.
By matching the coefficients of corresponding powers of x, we unlock our system of equations:
1. p+q=a (from x3)
2. pq=3a−4 (from x2)
3. 2(q−p)=2(a−1)⟹q−p=a−1 (from x)
**Step 3: Solve the linear system for p and q.**
We can use equations (1) and (3) to easily isolate p and q in terms of a.
Add equations (1) and (3) together to eliminate p:
(p+q)+(q−p)=a+(a−1)
2q=2a−1⟹q=a−21
Subtract equation (3) from (1) to eliminate q:
(p+q)−(q−p)=a−(a−1)
2p=1⟹p=21
**Step 4: Substitute and isolate a.**
Now, plug our unlocked p and q values into the middle equation (2): pq=3a−4.
21(a−21)=3a−4
Multiply the entire equation by 4 to clear the fractions and simplify the battlefield:
2(a−21)×2=(3a−4)×4
2a−1=12a−16
Group the a terms to secure the final value:
15=10a⟹a=1015=23
Step 5: Tally the valid values.
The math yields exactly one real, working value for a (which is 1.5). The question specifically asks for the *number of values* a can take.
Since there is only one valid solution, the count is 1.
Final Answer: 1