Simplify 3x(x + 2) - 5x(x - 3) + 7.
- AOption (a)
2x2 + 21x + 7
- BOption (b)
2x2 + 11x + 7
- COption (c)
-2x2 + 21x + 6
- DOption (d)
-2x2 + 21x + 7
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Correct answer
-2x2 + 21x + 7
Why this answer is correct
Shortcut Trick
Identify the coefficients of like terms directly:
For x2 terms: 3 − 5 = −2
For x terms: (3 × 2) − (5 × −3) = 6 + 15 = 21
For constants: 7
Resulting expression: −2x2 + 21x + 7
∴ The correct answer is −2x2 + 21x + 7.
Alternate Method
Given: 3x(x + 2) − 5x(x − 3) + 7
Formula Used: Distributive Property: a(b + c) = ab + ac
⇒ 3x(x) + 3x(2) − [5x(x) − 5x(3)] + 7
⇒ 3x2 + 6x − [5x2 − 15x] + 7
⇒ 3x2 + 6x − 5x2 + 15x + 7
⇒ (3x2 − 5x2) + (6x + 15x) + 7
⇒ −2x2 + 21x + 7
The simplified expression matches the value given in Option 4.
∴ The correct answer is −2x2 + 21x + 7.
Additional Information
Distributive Property
It states that multiplying a sum by a number is the same as multiplying each addend by the number and then adding the products: a(b + c) = ab + ac.
Combining Like Terms
Terms with the same variable and exponent can be combined by adding or subtracting their coefficients.
Sign Rules in Multiplication
When multiplying a negative number by another negative number, the result is always positive: (−a) × (−b) = +ab.





