CAT 2025 Slot2 Quant: the product of all possible values of x is:
March 6, 2026 2026-03-06 18:26CAT 2025 Slot2 Quant: the product of all possible values of x is:
AZUCATION • CAT QA Series
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#Algebra
#Exponents
CAT 2025 Slot 2
If $9^{x^2+2x-3} - 4 \left( 3^{x^2+2x-2} \right) + 27 = 0$, then the product of all possible values of $x$ is:
A
5
B
20
C
30
D
15
âš¡ AZUCATION SHORTCUT:
Substitute $3^{x^2+2x-3} = t$. Equation becomes $t^2 - 12t + 27 = 0$.
Roots are $t=9, 3$.
Powers: $x^2+2x-3 = 2$ and $x^2+2x-3 = 1$.
Product of roots from Eq 1 is $-5$; from Eq 2 is $-4$.
Total Product $= (-5) \times (-4) = \mathbf{20}$.
Substitute $3^{x^2+2x-3} = t$. Equation becomes $t^2 - 12t + 27 = 0$.
Roots are $t=9, 3$.
Powers: $x^2+2x-3 = 2$ and $x^2+2x-3 = 1$.
Product of roots from Eq 1 is $-5$; from Eq 2 is $-4$.
Total Product $= (-5) \times (-4) = \mathbf{20}$.
Detailed Step-by-Step Solution
Step 1: Use Substitution
Let $k = x^2 + 2x - 3$. Rewrite the terms:
$9^k - 4(3^{k+1}) + 27 = 0$
$(3^k)^2 - 12(3^k) + 27 = 0$.
Step 2: Solve the Quadratic in $3^k$
Let $3^k = t$. Then $t^2 - 12t + 27 = 0 \implies (t-9)(t-3) = 0$.
So, $3^k = 9 \implies k = 2$ OR $3^k = 3 \implies k = 1$.
Step 3: Solve for $x$ and find the product
1. $x^2 + 2x - 3 = 2 \implies x^2 + 2x - 5 = 0$. Product of roots ($x_1 x_2$) $= -5$.
2. $x^2 + 2x - 3 = 1 \implies x^2 + 2x - 4 = 0$. Product of roots ($x_3 x_4$) $= -4$.
Product of all values $= (-5) \times (-4) = \mathbf{20}$.